Direct Assay Method Research Articles

Study of the Prevalence of Animal Rabies in Guinea During the Year 2022

This study aimed to investigate the prevalence of rabies in dogs and other domestic animals, including two sheep, using data collected from the regional veterinary laboratories in Labé, Kankan, and Nzérékoré. In total, 44 samples were submitted to these veterinary laboratories and analyzed using the direct immunofluorescence assay method. This technique is the standard diagnostic procedure recommended for rabies by both the World Health Organization (WHO) and the World Organization for Animal Health (WOAH). The results of the testing revealed a high prevalence of rabies, estimated at 84.09%, with 37 out of the 44 samples testing positive for the disease. Rabies is commonly associated with dogs, which are well-known carriers of the virus. However, it is important to recognize that rabid dogs can transmit the disease to a wide range of mammals through bites, scratches, and other forms of contact. Consequently, farm animals such as cattle, sheep, goats, and other domestic species are also at risk. Once these animals are bitten by a rabid dog, they can contract the disease and, in many cases, succumb to its effects. This underscores the importance of monitoring and controlling rabies not only in dogs but also in other animals that might be exposed to this fatal disease. Another major piece of information is that only animals that showed signs of rabies and were slaughtered for this purpose or died naturally were analyzed.

Exploring the therapeutic potential of ruthenium(II)-bis(benzimidazol-2-yl)pyridine complex on MDA-MB-231, HCT-116 and normal L6 cell lines

The in vitro anticancer efficacy and cytotoxicity of the [Ru(bbp)2]2+ complex (bbp = 2,6-bis(benzimidazol-2-yl) pyridine) on human breast cancerous MDA-MB-231, colorectal HCT-116, and normal cell lines were investigated by direct microscopic and MTT assay methods. The synthesised [Ru(bbp)2]2+ complex was characterised by UV–visible, FTIR, 1H NMR, and MALDI-TOF-MS spectroscopic techniques. The complex showed a metal-to-ligand charge transfer (MLCT) absorption peak at 481 nm. The FTIR spectrum of the complex showed absorption bands in the range of 3458–573 cm−1. The 1H NMR chemical shift values resembled those of the bbp ligand. The molecular ion peak (M+) of the [Ru(bbp)2]2+ complex was obtained at m/z 1013.48. The IC50 values of the complex on MDA-MB-231, HCT-116 and normal L6 cell lines were calculated from the percentage cellular viability and are found to be 28.71, 9.06 and 153.82 µM respectively. The morphological changes in the cell lines at various concentrations of the complex were attributed to the generation of reactive oxygen species (ROS). The obtained result revealed that the anticancer activity of the synthesised complex depends on the concentration of the complex. The complex reduced the proportion of viable cells in both malignant cell lines, causing apoptosis. The results suggeseted that the synthesised complex showed good anticancer activity on the MDA-MB-231 and HCT-116 cell lines with low cytotoxicity. Thus, the present investigation paved the way for the development of novel anticancer drugs.

Concordance of LDL-C Estimating Equations with Direct Enzymatic Measurement in Diabetic and Prediabetic Subjects.

Low-density lipoprotein cholesterol (LDL-C) is a well-established biomarker in the management of dyslipidemia. Therefore, we aimed to evaluate the concordance of LDL-C-estimating equations with direct enzymatic measurement in diabetic and prediabetic populations. The data of 31,031 subjects included in the study were divided into prediabetic, diabetic, and control groups according to HbA1c values. LDL-C was measured by direct homogenous enzymatic assay and calculated by Martin-Hopkins, Martin-Hopkins extended, Friedewald, and Sampson equations. The concordance statistics between the direct measurements and estimations obtained by the equations were evaluated. All equations evaluated in the study had lower concordance with direct enzymatic measurement in diabetic and prediabetic groups compared to the non-diabetic group. Even so, the Martin-Hopkins extended approach demonstrated the highest concordance statistic in diabetic and prediabetic patients. Further, Martin-Hopkins extended was found to have the highest correlation with direct measurement compared with other equations. Over the 190 mg/dL LDL-C concentrations, the equation with the highest concordance was again Martin-Hopkins extended. In most scenarios, the Martin-Hopkins extended performed best in prediabetic and diabetic groups. Additionally, direct assay methods can be used at low values of the non-HDL-C/TG ratio (<2.4), as the performance of the equations in LDL-C estimation decreases as non-HDL-C/TG decreases.

Comparison of the optimized direct spectrophotometric serum prolidase enzyme activity assay method with the currently used spectrophotometric assay methods and liver fibrosis indexes to distinguish the early stages of liver fibrosis in patients with chronic hepatitis B infection.

The aim of this study was to optimize the currently used direct spectrophotometric serum prolidase enzyme activity (SPEA) assay method and compare its diagnostic accuracy with current precipitation and direct spectrophotometric assay methods, AST-to-ALT ratio, age platelet index, AST-to-platelet ratio index, cirrhosis discriminate score, Doha score, FIB-4, FibroQ, fibrosis index, Goteborg University Cirrhosis Index , King's score, and Pohl score for distinguishing Ishak F0 from F1-F3 in patients with chronic hepatitis B (CHB) infection. Liver biopsy results from 112 patients were included in this study. The SPEA values were 529(292-794) U/L, 671(486-927) U/L, and 1077(867-1399) U/L with the precipitation, current, and optimized direct spectrophotometric assay methods, respectively. According to multivariate logistic regression analysis optimized direct spectrophotometric SPEA was the only statistically significant parameter to predict the early stages of liver fibrosis. Optimized direct spectrophotometric SPEA assay method could be used to distinguish early stages of liver fibrosis in patients with CHB infection instead of the currentlyused spectrophotometric SPEA assay methods and other evaluated liver fibrosis indexes.

Levels of Deoxynivalenol and Aflatoxin Mycotoxins in Grains in Some Markets of Makurdi Metropolis, Nigeria

This study aimed to estimate deoxynivalenol (DON) and total aflatoxin in two varieties of millet, sorghum and maize, in some markets of Makurdi metropolis, North-Central, Nigeria using direct competitive Enzyme-linked Immunosorbent Assay (ELISA) method. Moisture content, total aerobic microbial count, mould count, Coliform and Escherichia coli were determined using standard analytical methods. Moisture content profile of 9.5032 to 12.9940% (sorghum), 9.5932 to 12.3604% (maize) and 9.0279 to 12.4108% (millet) was considered relatively high. Proliferation of total aerobic microbial count was observed in the samples across the sampling points. Mycotoxins under study were detected in all samples across the sampling points. Whereas total aflatoxins were within permissible limits, DON exceeded thresholds. It was also observed that, these grains were more susceptible to the fungus Fusarium species producer of DON than the producer of aflatoxin, thus susceptibility of the grains to fungus producer of DON was in the order: sorghum &gt; maize &gt; millet, whereas the susceptibility against the fungus producer or producers of total aflatoxin level was in the order: sorghum &gt; millet &gt; maize respectively. This in general, indicated microbial contamination of these cereals in the study location indicting farmers and marketers of poor hygienic handling and processing of the grains. Pearson’s 2-tailed correlation at 0.05 level of significance revealed strong correlation of deoxynivalenol with moisture content of grains across locations.

An international, interlaboratory ring trial confirms the feasibility of an extraction-less "direct" RT-qPCR method for reliable detection of SARS-CoV-2 RNA in clinical samples.

Reverse transcription–quantitative polymerase chain reaction (RT-qPCR) is used worldwide to test and trace the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). “Extraction-less” or “direct” real time–reverse transcription polymerase chain reaction (RT-PCR) is a transparent and accessible qualitative method for SARS-CoV-2 detection from nasopharyngeal or oral pharyngeal samples with the potential to generate actionable data more quickly, at a lower cost, and with fewer experimental resources than full RT-qPCR. This study engaged 10 global testing sites, including laboratories currently experiencing testing limitations due to reagent or equipment shortages, in an international interlaboratory ring trial. Participating laboratories were provided a common protocol, common reagents, aliquots of identical pooled clinical samples, and purified nucleic acids and used their existing in-house equipment. We observed 100% concordance across laboratories in the correct identification of all positive and negative samples, with highly similar cycle threshold values. The test also performed well when applied to locally collected patient nasopharyngeal samples, provided the viral transport media did not contain charcoal or guanidine, both of which appeared to potently inhibit the RT-PCR reaction. Our results suggest that direct RT-PCR assay methods can be clearly translated across sites utilizing readily available equipment and expertise and are thus a feasible option for more efficient COVID-19 coronavirus disease testing as demanded by the continuing pandemic.

EVALUATION OF MOULD AND TOTAL AFLATOXIN CONTENT IN RAW AND PROCESSED GROUNDNUT (ARACHIS HYPOGAEA L.) PRODUCTS FROM AN EXTENSIVE AGRARIAN STATE IN CENTRAL-NIGERIA.

Fifty-four samples of groundnut products (including control and purchased) were collected from several locations in Benue State-Nigeria and assessed for total Aflatoxins (TAF) using Direct Competitive Enzymes-linked Immunosorbent Assay method (ELISA). Microbial isolation, identification and estimation was made for all samples. The results implied that TAF were detected in 100 % of the groundnut products. The highest incidence of TAF occurred in the paste (6.30 -10.26 µg/kg) followed by oil (0.53- 8.00 µg/kg) and cake (0.36-3.00 µg/kg). These levels were however below the 20 μg/kg maximum permissible limits (MPL) set by National Agency for Food and Drug Administration and Control (NAFDAC) in Nigeria and the 10 μg/kg limit of the Codex Alimentarius Commission (CAC). In addition, the results showed a strong positive correlation between the moisture content and the concentration of aflatoxin. Mould count/isolation results identified a total of 305 isolates with Aspergillus flavus having an occurrence of 137 (44.92 %) being the major isolate among others. There was no significant difference in the levels of total aflatoxin between the processed and purchased groundnut samples. The TAF reported in these products are likely to be infiltrated from raw groundnuts from the farm, during storage or handling. This paper is the first in the study area that documents the importance in routine check for aflatoxin content in groundnut products which is vital in reducing chances of aflatoxin poisoning from these products.

A stable and sensitive enzyme-linked immunosorbent assay (ELISA) for the determination of metsulfuron-methyl residues in foods.

A hapten of metsulfuron-methyl was successfully designed and synthesized from 2-methylester-phenylsulfonamide and succinic anhydride, and the polyclonal antibody against metsulfuron-methyl was prepared by immunization procedure with the hapten-bovine serum albumin conjugate. A stable and sensitive direct competitive enzyme-linked immunosorbent assay (dcELISA) method had been developed under the optimal conditions. The sensitivity (IC50 ) was 37.03± 1.87µg/L, and the detection line (IC15 ) was 1.57± 0.11µg/L. Rice, wheat, oat, flaxseed, milk, and water were chosen to study the recovery test and the recovery rates were 83.11%-117.44% . The matrix effect was eliminated by a simple dilution of the sample extracts. The results from dcELISA were well agreement with the results from HPLC-MS. It was indicated that the developed method had good accuracy and stability. It could be applied for the detection of metsulfuron-methyl residues. It was worth mentioning that the antibody could recognize metsulfuron-methyl and tribenuron-methyl with cross-reactivities of 100% and 49.72%, respectively. In order to understand the cross-reactivity, molecular modeling including molecular alignment and electrostatic potential surfaces were introduced. It was found that the special group of metsulfuron-methyl played an important role, especially on C3 position of the phenyl group. PRACTICAL APPLICATION: A stable, sensitive, and low-cost dc ELISA method had been developed with good accuracy and applied in the determination of metsulfuron-methyl in foods. Molecular simulation was introduced to understand the specificity between the antibody and the analyst. It was a good method to study the cross-reactivity between the antibody and the analyst or analogue.

Detection of 4 quinolone antibiotics by chemiluminescence based on a novel Nor-Biotin bifunctional ligand and SA-ALP technology.

A simple and effective direct competitive chemiluminescence immunoassay for the detection of 4 kinds of quinolone antibiotics in milk was established using Nor-Biotin (biotin-modified norfloxacin [NOR]) bifunctional ligand and alkaline phosphatase-conjugated streptavidin signal amplification technology. The polyclonal antibody was obtained after the immunization of New Zealand White rabbits using norfloxacin-derived antigen. "Click chemistry" was used for the rapid and facile synthesis of the Nor-Biotin bifunctional ligand. After the optimization of the incubation time and reaction buffer, the direct competitive chemiluminescence assay method was developed and used for sensitive detection of 4 kinds of quinolone drugs (NOR, pefloxacin, ciprofloxacin, and danofloxacin). The IC50 of the 4 kinds of quinolone drugs ranged from 7.35 to 24.27 ng/mL, and the lowest detection limits ranged from 0.05 to 0.16 ng/mL, which were below their maximum residue levels, approved by the EU for treatment of food-producing animals. To demonstrate the applicability of the assay, artificially contaminated milk samples with the 4 quinolone drugs were analyzed. The mean recovery rates of the drugs ranged from 86.31% to 112.11%.

Does vitamin D affect the association between FTO rs9939609 polymorphism and depression?

ABSTRACT Background & objectives: Depression is a highly prevalent and multifactorial psychological disorder. Fat Mass and Obesity-Associated (FTO) gene and the serum vitamin D level are proposed to be involved in pathophysiology of depression. This study aimed to investigate the interactions between one FTO gene single nucleotide polymorphism, depression, and serum vitamin D level in overweight adults. Methods: One hundred and ninety-seven overweight adults were recruited in this cross-sectional study. FTO genotyping was performed by amplification refractory mutation system polymerase chain reaction (ARMS-PCR). Depression severity was assessed using Beck’s depression inventory (BDI-II). Serum vitamin D levels were measured using a direct competitive enzyme-linked immunosorbent assay (ELISA) method. Results: A-allele carriers had higher Beck’s depression score (P = 0.03). Multivariate regression models showed a positive association between the A-allele of FTO rs9939609 polymorphism and depression. Serum vitamin D level had no effect on the association between FTO genotype and depression. Conclusion: A-allele of FTO rs9939609 polymorphism might be associated with depression independent of serum vitamin D level. Further longitudinal studies are needed to confirm these results.

Solid-state potentiometric sensor for the rapid assay of the biologically active biogenic amine (tyramine) as a marker of food spoilage

Tyramine (TYR) is a vasoactive biogenic amine found in food products due to improper storage and poor hygiene. High TYR intake results in a wide range of life-threatening physiological reactions. The work optimizes a solid-state potentiometric sensor in the absence of a reported potentiometric method for rapid and direct TYR assay. The optimization study included thirteen membrane cocktails of different compositions. The optimized sensor proved a near-Nernstian slope of 57.30 mV/decade, a quantification limit of 10.6 ppm, and a detection limit of 7.9 ppm. Validation results confirmed the sensor ability for the direct assay of TYR in blue cheese, aged cheese, Egyptian pickled cottage cheese, and pickled herring. A comparison with the reported chromatographic method expresses the merits and potentials of the developed sensor for the rapid testing of food edibility, quality, and safety based on its TYR content.Chemical compounds studied in this article: Tyramine (PubChem CID: 5610); Tyramine hydrochloride (PubChem CID: 66449); Poly(vinyl chloride) (PubChem SID: 24864273); Tricresyl phosphate (PubChem CID: 6529); sodium phosphotungstate tribasic hydrate (PubChem SID: 329753864).

A New Perspective on the Status of the Intestinal Parasitic Infections in the Rural Areas of Fars Province South of Iran

Parasitoses are among the most important problems of most countries especially developing countries. We aimed to detect the situation of intestinal parasitic infections in the Farashband district in Fars Province South of Iran and identify influential factors in the escalation of parasitic diseases and to reduce them. Overall, 1009 participants from the age of 6 months to 90 years were selected from 3 cities and 15 villages of Farashband district, Fars Province South of Iran from 2015 to 2016. Parasitological methods such as the direct assay method, formalin-ether concentration method, and zinc sulfate flotation were used for diagnosis of worm eggs, cysts, and protozoa trophozoite. Susceptible and protozoan positive samples were stained using the Trichrome staining method. The modified acid-fast staining procedure was conducted for diarrheal samples and the results were used for diagnosis of coccidia. Overall, 313 subjects were infected with at least one intestinal parasite (pathogenic and nonpathogenic). Helminthes infection and protozoan infection were observed in 9 (0.9%) and 304 (30.13%) participants, respectively. Fecal samples of 34 patients with diarrheal feces were used to prepare smears for further examinations using the Ziehl-Neelsen staining method. Examinations showed no infection with coccidia. Helminthes infection has decreased drastically but protozoan infection is still considered a health issue in this region. It is possible to reduce parasitic infections through proper measures such as increasing public awareness and education the public, especially children on health problems with education courses.

Detection of Kappa Light Chain Protein in Human Urine by Surface Plasmon Resonance

Ingredients of urine proteins are complex, and different types of urinary proteins are usually associated with different diseases. Light chain proteins are related to neoplastic diseases, which might be misdiagnosed as nephropathia. Accurate detection of urine light chain proteins in urine is very important for early diagnosis of multiple myeloma and other diseases. Traditional methods for detecting urinary light chain proteins are of low sensitivities, complex processes and high costs. Surface plasmon resonance (SPR) is a sensitive, real-time and label-free method which is suitable for studying protein-molecule interactions. In this paper, SPR methods were used to detect kappa light chain proteins through direct assay method. Kappa light chain protein antibodies with a pH value of 5.0 were successfully immobilized to the sensor chip in one channel while another was used as a reference channel. Detection limit of kappa light chain proteins was estimated to be 0.1 μg/mL through direct assay method in standard solution. Healthy and patient human urine samples were also tested, which showed different SPR response signals. It indicated that SPR could be used as a fast and sensitive method in quantitative detection of urinary kappa proteins.

Development of biomimetic enzyme-linked immunosorbent assay based on molecular imprinting technique for semicarbazide detection

ABSTRACT Herein, we present a direct competitive biomimetic enzyme-linked immunosorbent assay (BELISA) method for the determination of semicarbazide (SEM) using a molecularly imprinted polymer (MIP) film as the bionic antibody. The best monomer (methacrylic acid) and molar ratio of monomer to template (4:1) were determined with the aid of computational simulation methods based on density functional theory (DFT). The MIP film was characterised by scanning electron microscopy and adsorption experiments. The results showed that the imprinted film was successfully synthesised with good adsorption performance. Under optimal conditions, the calibration curve was linear in the range of 1.0–1.0×104 ng/mL (R 2 = 0.9863). The detection limit (IC15) and sensitivity (IC50) were 1.0 and 85.7 ng/mL, respectively. This BELISA method was further applied to the analysis of SEM in food samples; recoveries ranged from 86.1% to 90.8%. These observations indicated that the developed method could be adapted for SEM quantification in food.

Association of serum lipid levels with depression

Introduction and Objectives: Depression is a type of mood disorder. It is considered as one among the major health problems worldwide as it is highly prevalent in general population and leads to significant loss of quality of life and social functioning in the affected individual. It has been postulated that changes in the cholesterol content of the synaptosomal membrane leads to decrease in the number of serotonin receptors due to decrease in cholesterol concentration leading to depression. Nevertheless, there are contradictory opinions about the association of serum lipid levels and depression. Thus, the present study was undertaken to study the association of serum lipid levels with depression. Materials and Methods: A case control study was conducted including 100 age and sex matched diagnosed cases of depression and 100 age and sex matched healthy individuals as controls. In all the subjects, serum levels of triglycerides (TG) was estimated by GPO-PAP method, total cholesterol (TC) by CHOD-PAP method, LDL cholesterol (LDL-C) by direct assay and HDL cholesterol (HDL-C) by CHOD-PAP method. Results were expressed as mean SD. Student’s independent t-test was used for comparing the means of two groups. Relationship between parameters was assessed by Pearson’s correlation coefficient by using SPSS (Statistical package for social sciences) software version 19. For all the tests, the probability value (p-value) of less than 0.05 is considered statistically significant. Results: Serum levels of TC were significantly lower in cases of depression compared to controls and found no difference with TG, LDL-C and HDL-C levels. We also observed from the results that, there was a negative correlation between TG, TC, LDL-C and HRSD scores which was found to be highly significant statistically. Conclusion: In conclusion, serum TC level was significantly lower in depression cases compared to controls and also has high negative correlation with HRSD score. Thus, the patients wi

Field Test and Validation of the Multiplier Measles, Mumps, Rubella, and Varicella-Zoster Multiplexed Assay System in the Democratic Republic of the Congo by Using Dried Blood Spots.

Here we describe baseline validation studies and field performance of a research-use-only chemiluminescent multiplex serology panel for measles, mumps, rubella, and varicella-zoster virus used with dried blood spots in support of the 2013-2014 Democratic Republic of the Congo Demographic and Health Survey. Characterization of the panel using U.S. FDA-cleared commercial kits shows good concordance for measles, mumps, rubella, and varicella-zoster with average sensitivity across assays of 94.9% and an average specificity of 91.4%. As expected, performance versus available standards validated for plaque-reduction assays does not provide a 1:1 correspondence with international units and yet demonstrates excellent linearity (average Hill's slope = 1.02) and ∼4 logs of dynamic range. In addition, for the four assays, the multiplexed format allowed for inclusion of three positive and two negative controls for each sample. A prototype Dynex Multiplier chemiluminescent automated immunoassay instrument with a charge-coupled device camera provided a rugged and robust processing and data acquisition platform. Performance of a multiplex instrument for serological testing in a substantially resource-limited environment shows excellent reproducibility, minimal cross-reactivity, and a clear discrimination between specific assays and should be considered a viable option for future serosurveys.IMPORTANCE The critical evaluation of immunization programs is key to identifying areas of suboptimal vaccination coverage, monitoring activities, and aiding development of public health policy. For evaluation of vaccine effectiveness, direct antibody binding assay methods, including enzyme immunoassay, enzyme-linked fluorescence assays, and indirect immunofluorescence assay, are most commonly used for detection of IgG antibodies. However, despite their well-demonstrated, reliable performance, they can be labor-intensive and time-consuming and require separate assays for each individual marker. This necessitates increased sample volumes, processing time, and personnel, which may limit assessment to a few key targets in resource-limited settings, that is, low- and middle-income locations where funding for public health or general infrastructure that directly impacts public health is restricted, limiting access to equipment, infrastructure, and trained personnel. One solution is a multiplexed immunoassay, which allows for the detection of multiple analytes in a single reaction for increased efficiency and rapid surveillance of infectious diseases in limited-resource settings. Thus, the scope of the project precluded a full validation, and here we present abbreviated validation studies demonstrating adequate sensitivity, specificity, and reproducibility.

Diagnosis of Fungal and Bacterial Diseases Based on Symptom &amp; Sign

Plant disease diagnosis is a form of hypothesis testing, where the hypothesis is simply the identity of the disease, and a good diagnostician goes through multiple iterations of the scientific method (seeking evidence through testing that supports or refutes the hypothesis that s/he generates). Identification of affected plants is one of the first steps in diagnosing a plant disease. Diagnosis is one of the most important aspects of a plant pathologist's training. Both scientific and common names of the plant should be noted. Without proper identification of the disease and the disease-causing agent, disease control measures can be a waste of time and money and can lead to further plant losses. Fungi are small, generally microscopic, eukaryotic, usually filamentous, branched, spore-bearing organisms that lack chlorophyll. Bacteria are prokaryotes. These are generally single-celled microorganisms whose genetic material (DNA) is not bound by a membrane and therefore is not organized into a nucleus. Our general objective was to acquaintance with Plant pathology laboratory materials & make disease diagnosis from field up to laboratory based on symptom and signs from different plant samples. All most all necro-tropic and bio-tropic fungi are grown on PDA agar, but bio-tropic fungi and bacterial diseases cannot grow on PDA agar. The best preferable method to diagnosis bio-tropic fungi is using direct leaf assay and blotting method on petri-dish. For bacterial disease identification we use NA agar. From this laboratory work I had concluded that those fungal and bacterial diseases need their niche to grow and well identified. It is very difficult to identify plant diseases based on sign and symptom. It is very imperative to diagnosis plant disease by collaborating both conventional (using sign and symptom) and molecular methods. It needs further work to identify rust diseases using race analysis up to f. species level.

Dose-Response-Time Data Analysis: An Underexploited Trinity.

The most common approach to in vivo pharmacokinetic and pharmacodynamic analyses involves sequential analysis of the plasma concentration- and response-time data, such that the plasma kinetic model provides an independent function, driving the dynamics. However, in situations when plasma sampling may jeopardize the effect measurements or is scarce, nonexistent, or unlinked to the effect (e.g., in intensive care units, pediatric or frail elderly populations, or drug discovery), focusing on the response-time course alone may be an adequate alternative for pharmacodynamic analyses. Response-time data inherently contain useful information about the turnover characteristics of response (target turnover rate, half-life of response), as well as the drug's biophase kinetics (biophase availability, absorption half-life, and disposition half-life) pharmacodynamic properties (potency, efficacy). The use of pharmacodynamic time-response data circumvents the need for a direct assay method for the drug and has the additional advantage of being applicable to cases of local drug administration close to its intended targets in the immediate vicinity of target, or when target precedes systemic plasma concentrations. This review exemplifies the potential of biophase functions in pharmacodynamic analyses in both preclinical and clinical studies, with the purpose of characterizing response data and optimizing subsequent study protocols. This article illustrates crucial determinants to the success of modeling dose-response-time (DRT) data, such as the dose selection, repeated dosing, and different input rates and routes. Finally, a literature search was also performed to gauge how frequently this technique has been applied in preclinical and clinical studies. This review highlights situations in which DRT should be carefully scrutinized and discusses future perspectives of the field.

Development of direct competitive biomimetic immunosorbent assay based on quantum dot label for determination of trichlorfon residues in vegetables

A direct competitive biomimetic immunosorbent assay method based on molecularly imprinted polymer was developed for the determination of trichlorfon. A CdSe/ZnS quantum dot label was used as the marker. The hydrophilic imprinted film was synthesized directly on the surface of a 96-well plate, and characterized by Fourier-transform infrared spectroscopy and thermo-gravimetric analyses. The method exhibited high stability, selectivity, and sensitivity. Under optimal conditions, the limits of detection and sensitivity of the biomimetic immunosorbent assay method were 9.0 μg L−1 and 5.0 mg L−1 (0.1 mg kg−1 and 62.5 mg kg−1 for vegetable sample), respectively. Low cross-reactivity values of 19.2% and 15.6% were obtained for the structural analogues. Spinach and rape samples spiked with trichlorfon were extracted and determined by this method with recoveries ranging from 83.6% to 91.1%. The method was applied for the detection of trichlorfon residues in leek and cucumber samples, and results correlated well with those obtained using GC.

Direct Resazurin Microplate Assay in Drug Susceptibility Testing of Smear-Positive Sputum Samples against Mycobacterium tuberculosis.

BackgroundA new direct microplate-based colorimetric drug susceptibility test that omits the initial isolation of Mycobacterium tuberculosis from sputum specimens was evaluated.MethodsA total of 51 M. tuberculosis acid fast bacilli (AFB) smear-positive sputum specimens were inoculated directly into drug-free and serial dilutions of drug-containing Middlebrook 7H9 broth media. With this direct resazurin micro plate assay (REMA) method, resazurin dye was used as a growth indicator in microplate wells. The minimum inhibitory concentrations (MIC) of isoniazid (INH) and rifampicin (RIF) were compared with those of the ‘gold standard’ absolute concentration method (ACM). The turnaround time (TAT) of the direct REMA and the ACM were also determined.ResultsAt the selected cut-off points (INH: 0.0625 μg/mL; RIF: 0.125 μg/mL), good drug susceptibility test results were obtained for INH and RIF with an average sensitivity, specificity and accuracy of 90%, 100% and 97%, respectively, with a TAT of 15 days. The REMA method also correctly classified the resistant isolates with positive predictive values of 95% and negative predictive values of 98% for the two drugs.ConclusionsThe direct REMA was reliable in routine diagnostic laboratories for the drug susceptibility testing of M. tuberculosis and the rapid detection of multi-drug-resistant tuberculosis.