Immunoprotective effect of an in silico designed multiepitope cancer vaccine with BORIS cancer-testis antigen target in a murine mammary carcinoma model

In our previous study, immunoinformatic tools were used to design a novel multiepitope cancer vaccine based on the most immunodominant regions of BORIS cancer-testis antigen. The final vaccine construct was an immunogenic, non-allergenic, and stable protein consisted of multiple cytotoxic T lymphocytes epitopes, IFN-γ inducing epitopes, and B cell epitopes according to bioinformatic analyzes. Herein, the DNA sequence of the final vaccine construct was placed into the pcDNA3.1 vector as a DNA vaccine (pcDNA3.1-VAC). Also, the recombinant multiepitope peptide vaccine (MPV) was produced by a transfected BL21 E. coli strain using a recombinant pET-28a vector and then, purified and screened by Fast protein liquid chromatography technique (FPLC) and Western blot, respectively. The anti-tumor effects of prophylactic co-immunization with these DNA and protein cancer vaccines were evaluated in the metastatic non-immunogenic 4T1 mammary carcinoma in BALB/c mice. Co-immunization with the pcDNA3.1-VAC and MPV significantly (P < 0.001) increased the serum levels of the MPV-specific IgG total, IgG2a, and IgG1. The splenocytes of co-immunized mice exhibited a significantly higher efficacy to produce interleukin-4 and interferon-γ and proliferation in response to MPV in comparison with the control. The prophylactic co-immunization regime caused significant breast tumors' growth inhibition, tumors' weight decrease, inhibition of metastasis formation, and enlarging tumor-bearing mice survival time, without any considerable side effects. Taking together, this cancer vaccine can evoke strong immune response against breast tumor and inhibits its growth and metastasis.

Comparison of back propagation network and radial basis function network in Departure from Nucleate Boiling Ratio (DNBR) calculation

Since estimating the minimum departure from nucleate boiling ratio (MDNBR) requires complex calculations, an alternative method has always been considered. One of these methods is neural network. In this study, the Back Propagation Neural network (BPN) and Radial Basis Function Neural network (RBFN) are introduced and compared in order to estimate MDNBR of the VVER-1000 light water reactor. In these networks, the MDNBR were predicted with the inputs including core mass flux, core inlet temperature, pressure, reactor power level and position of the control rods. To obtain the data required to design these neural networks, an externally coupledcode was developed and its ability to estimate the thermo-hydraulic parameters of the VVER-1000 reactor was compared with other numerical solutions of this benchmark and the Final Safety Analysis Report (FSAR). After ensuring the accuracy of this coupled-code, MDNBR was calculated for 272 different conditions of reactor operating, and it was used to design BPN and RBFN. Comparison of these two neural networks revealed that when the output SMEs of the two systems were approximately the same, the training process in RBFN was much faster than in BPN and the maximum network error in RBFN was less than in BPN.

Exploring the cancer-testis antigen BORIS to design a novel multi-epitope vaccine against breast cancer based on immunoinformatics approaches

Recently, cancer immunotherapy has gained lots of attention to replace the current chemoradiation approaches and multi-epitope cancer vaccines are manifesting as the next generation of cancer immunotherapy. Therefore, in this study, we used multiple immunoinformatics approaches along with other computational approaches to design a novel multi-epitope vaccine against breast cancer. The most immunogenic regions of the BORIS cancer-testis antigen were selected according to the binding affinity to MHC-I and II molecules as well as containing multiple cytotoxic T lymphocyte (CTL) epitopes by multiple immunoinformatics servers. The selected regions were linked together by GPGPG linker. Also, a T helper epitope (PADRE) and the TLR-4/MD-2 agonist (L7/L12 ribosomal protein from mycobacterium) were incorporated by A(EAAAK)3A linker to form the final vaccine construct. Then, its physicochemical properties, cleavage sites, TAP transport efficiency, B cell epitopes, IFN-γ inducing epitopes and population coverage were predicted. The final vaccine construct was reverse translated, codon-optimized and inserted into pcDNA3.1 to form the DNA vaccine. The final vaccine construct was a stable, immunogenic and non-allergenic protein that contained numerous CTL epitopes, IFN-γ inducing epitopes and several linear and conformational B cell epitopes. Also, the final vaccine construct formed stable and significant interactions with TLR-4/MD-2 complex according to molecular docking and dynamics simulations. Moreover, its world population coverage for HLA-I and HLA-II were about 93% and 96%, respectively. Taking together, these preliminary results can be used as an appropriate platform for further experimental investigations.Communicated by Ramaswamy H. Sarma.

Comparison of back propagation network and radial basis function network in Departure from Nucleate Boiling Ratio (DNBR) calculation

Since estimating the minimum departure from nucleate boiling ratio (MDNBR) requires complex calculations, an alternative method has always been considered. One of these methods is neural network. In this study, the Back Propagation Neural network (BPN) and Radial Basis Function Neural network (RBFN) are introduced and compared in order to estimate MDNBR of the VVER-1000 light water reactor. In these networks, the MDNBR were predicted with the inputs including core mass flux, core inlet temperature, pressure, reactor power level and position of the control rods. To obtain the data required to design these neural networks, an externally coupledcode was developed and its ability to estimate the thermo-hydraulic parameters of the VVER-1000 reactor was compared with other numerical solutions of this benchmark and the Final Safety Analysis Report (FSAR). After ensuring the accuracy of this coupled-code, MDNBR was calculated for 272 different conditions of reactor operating, and it was used to design BPN and RBFN. Comparison of these two neural networks revealed that when the output SMEs of the two systems were approximately the same, the training process in RBFN was much faster than in BPN and the maximum network error in RBFN was less than in BPN.

Exploring the out of sight antigens of SARS-CoV-2 to design a candidate multi-epitope vaccine by utilizing immunoinformatics approaches

SARS-CoV-2 causes a severe respiratory disease called COVID-19. Currently, global health is facing its devastating outbreak. However, there is no vaccine available against this virus up to now. In this study, a novel multi-epitope vaccine against SARS-CoV-2 was designed to provoke both innate and adaptive immune responses. The immunodominant regions of six non-structural proteins (nsp7, nsp8, nsp9, nsp10, nsp12 and nsp14) of SARS-CoV-2 were selected by multiple immunoinformatic tools to provoke T cell immune response. Also, immunodominant fragment of the functional region of SARS-CoV-2 spike (400-510 residues) protein was selected for inducing neutralizing antibodies production. The selected regions' sequences were connected to each other by furin-sensitive linker (RVRR). Moreover, the functional region of β-defensin as a well-known agonist for the TLR-4/MD complex was added at the N-terminus of the vaccine using (EAAAK)3 linker. Also, a CD4 + T-helper epitope, PADRE, was used at the C-terminal of the vaccine by GPGPG and A(EAAAK)2A linkers to form the final vaccine construct. The physicochemical properties, allergenicity, antigenicity, functionality and population coverage of the final vaccine construct were analyzed. The final vaccine construct was an immunogenic, non-allergen and unfunctional protein which contained multiple CD8 + and CD4 + overlapping epitopes, IFN-γ inducing epitopes, linear and conformational B cell epitopes. It could form stable and significant interactions with TLR-4/MD according to molecular docking and dynamics simulations. Global population coverage of the vaccine for HLA-I and II were estimated 96.2% and 97.1%, respectively. At last, the final vaccine construct was reverse translated to design the DNA vaccine. Although the designed vaccine exhibited high efficacy in silico, further experimental validation is necessary.

Efficacy of co-immunization with the DNA and peptide vaccines containing SYCP1 and ACRBP epitopes in a murine triple-negative breast cancer model

Multiepitope cancer vaccines have gained lots of attention for prophylactic and therapeutic purposes in cancer patients. In our previous study, multiepitope DNA and peptide cancer vaccines consisted of the most immunodominant epitopes of ACRBP and SYCP1 antigens were designed by bioinformatic tools. In this study, the effect of prophylactic co-immunization with these DNA and peptide cancer vaccines in the 4T1 breast cancer animal model was assessed. Serum levels of the peptide-specific IgG total, IgG2a and IgG1 were measured by enzyme-linked immunosorbent assay (ELISA). Also, the efficacy of the immunized mice splenocytes' for producing interleukin-4 (IL-4) and interferon-γ (IFN-γ) was evaluated. The co-immunization caused a significant (P < .05) increase in the serum levels of IgG1 and IgG2a. The co-immunized mice splenocytes exhibited significantly enhanced IL-4 (6.6-fold) and IFN-γ (19-fold) production. Also, their lymphocytes exhibited higher proliferation rate (3-fold) and granzyme B production (6.5-fold) in comparison with the control. The prophylactic co-immunization significantly decreased the breast tumors' volume (78%) and increased the tumor-bearing mice survival time (37.5%) in comparison with the control. Taking together, prophylactic co-immunization with these multiepitope DNA and peptide cancer vaccines can activate the immune system against breast cancer. However, further experiments are needed to evaluate their efficacy from different angles.

Spirulina extract enriched for Braun-type lipoprotein (Immulina®) for inhibition of 4T1 breast tumors' growth and metastasis

Spirulina platensis extracts have exhibited considerable anti-cancer effects. To investigate the efficacy of the Spirulina extract enriched for Braun-type lipoprotein (Immulina®) for breast cancer treatment, 4T1 breast tumor-bearing mice were treated with 40 mg/kg Immulina® daily and the tumors' growth and metastasis were assessed. Also, CD4, CD8, and CD56 staining were performed to investigate the Immulina® effect on the immune cells' recruitment to the tumors by immunohistochemistry. Immulina® could significantly (P < 0.001) inhibit 4T1 breast tumors' growth. Immulina®-treated group exhibited a 63% decrease in the tumors' volume in comparison with control (P < 0.001). Also, Immulina® could significantly (P < 0.001) decrease metastatic burden at the vital organs as 68% and 61% decrease in the liver and lungs metastatic colonies were observed, respectively. Also, Immulina® could increase mean survival time of the tumor-bearing mice for 29 days. The Spirulina-treated mice tumors contained significantly more infiltrated NK, CD4+, and CD8+ T lymphocytes in comparison with control. Taking together, Immulina® can be a safe anti-cancer supplement with the ability to cause direct apoptosis to the cancer cells and activate the immune system against tumor. This supplement with natural origin seems to have bright future to help breast cancer patients.

Identifying the Most Effective Hydatid Cyst Fluid Fraction for Anticancer Vaccination of 4T1 Breast Tumor-Bearing Mice

Background:

The hydatid cyst fluid antigens have high homology with cancer cell antigens and also exhibit considerable immunogenicity. Therefore, their utilization for cancer immunization can cause an effective antitumor immune response. However, the main challenge is identifying the most effective antigens for this purpose.

Methods:

Hydatid cyst fluid fractions including the glycolipid fraction, glycoprotein fraction, 78 kDa fraction, and antigen B fraction were prepared. Then, the BALB/c mice were immunized against different antigens and, subsequently, 4T1 cells were subcutaneously implanted. The tumors' growth, metastasis, and tumor-bearing mice survival were assessed in different immunized groups. In addition, IL-2, IL-4, IFN-γ, and TNF-α serum levels were estimated to evaluate the immune system response.

Results:

BALB/c mice immunization against the complete hydatid cyst fluid antigens exhibited more significant inhibition of the tumors' growth and metastasis and increase of tumor-bearing mice survival in comparison with its derived fractions. However, the 78 kDa fraction exhibited the best results according to the same factors in comparison with all the prepared fractions.

Conclusions:

The 78 kDa fraction of the hydatid cyst fluid was the most effective fraction of hydatid cyst fluid for immunization against 4T1 breast tumors.

Production, purification, and in vivo evaluation of a novel multiepitope peptide vaccine consisted of immunodominant epitopes of SYCP1 and ACRBP antigens as a prophylactic melanoma vaccine

Melanoma cells are significantly resistance to the current treatments. Therefore, the best option for high-risk populations is prevention. Recently, many preventive cancer vaccines have been developed. In our previous study, several bioinformatic tools were employed for selection of the most immunodominant epitopes of acrosin binding protein (ACRBP) and synaptonemal complex protein 1 (SYCP1) antigens to design multiepitope DNA and peptide cancer vaccines. In the current study, the final construct of the multiepitope DNA vaccine was placed into a pcDNA3.1 vector and then, subcloned into a pET-28a (+) expression vector for transfecting BL21 E. coli strain. The recombinant multiepitope peptide vaccine, weighing 6.35 kDa, was purified by Fast protein liquid chromatography technique (FPLC) and detected by western blotting. Subsequently, C57BL/6 mice were immunized by a mixture of the peptide vaccine and incomplete Freund's adjuvant (IFA) (four vaccinations with one-week intervals). Two weeks after the last vaccination, the serum levels of the peptide-specific IgG total, IgG2a, and IgG1 were measured by enzyme-linked immunosorbent assays (ELISA). Also, the immunized mice splenocytes efficacy for producing interleukin-4 (IL-4) and interferon-γ (IFN-γ) after stimulation with the peptide vaccine was evaluated. At last, the prophylactic effect of the peptide vaccine immunization was evaluated in B16-F10 murine melanoma model. The peptide vaccine immunization caused a significant increase in the serum levels of IgG1, IgG2a, and IgG2a. Also, the immunized mice splenocytes exhibited significantly higher ability to produce IL-4 (10-fold) and IFN-γ (16-fold) after stimulation with the peptide vaccine, in comparison with the PBS and IFA groups. The peptide immunized mice exhibited 50.2% and 43% decrease in the mean tumors' volume in comparison with PBS and IFA groups. Also, the mean survival time for the peptide immunized mice was 33 ± 1.3 days which was 5 and 6 days more than the PBS and IFA groups, respectively. The obtained results exhibit high efficacy of the designed multiepitope peptide vaccine for the immune system activation and anti-tumor prophylactic effects in the murine melanoma model.

In silico analysis of transmembrane protein 31 (TMEM31) antigen to design novel multiepitope peptide and DNA cancer vaccines against melanoma

Multiepitope cancer vaccines are announcing themselves as the future of melanoma treatment. Herein, high immunogenic regions of transmembrane protein 31 (TMEM31) antigen were selected according to cytotoxic T lymphocytes' (CTL) epitopes and major histocompatibility complex (MHC) binding affinity through in silico analyses. The 32-62, 77-105, and 125-165 residues of the TMEM31 were selected as the immunodominant fragments. They were linked together by RVRR and HEYGAEALERAG motifs to improve epitopes separation and presentation. In addition, to activate helper T lymphocytes (HTL), Pan HLA DR-binding epitope (PADRE) peptide sequence and tetanus toxin fragment C (TTFrC) were incorporated into the final construct. Also, the Beta-defensin conserved domain was utilized in the final construct as a novel adjuvant for Toll-like receptor 4/myeloid differentiation factor (TLR4-MD) activation. The CTL epitopes, cleavage sites, post-translational modifications, TAP transport efficiency, and B cells epitopes were predicted for the peptide vaccine. The final construct contained multiple CTL and B cell epitopes. In addition, it showed 93.55% and 99.13% population coverage in the world for HLA I and HLA II, respectively. According to these preliminary results, the multiepitope cancer vaccine can be an appropriate choice for further experimental investigations.

Deep eutectic-water binary solvent associations investigated by vibrational spectroscopy and chemometrics

Investigation of the behaviour of deep eutectic solvents (DESs) as novel green solvents in the presence of other solvents is of great interest. In this study the behaviour of a common natural DES, namely choline chloride-glycerol deep eutectic solvent (GDES), was studied in the presence of water. A detailed study of the association of the two solvents was performed by integration of two vibrational spectroscopic methods (FTIR and Raman spectroscopy) followed by multivariate analysis. Moreover, a binary mixture of glycerol (Gly) as one of the liquid constituents of GDES and water was explored under the same conditions. A quintuplet and ternary systems were resolved for GDES-water and Gly-water probes, respectively, using multivariate analysis of global data (multi-technique and multi-experiment data arrangements). The results confirmed that in the presence of water the GDES showed different behaviour from its components. Therefore, a DES can be introduced as an independent solvent with its unique properties. Also, different H-bond interaction energies of GDES and its pure components in the presence of water were shown by theoretical calculations based on a density functional theory framework. To investigate the effects of water on the structure of GDES, molecular dynamics (MD) simulations of GDES-water liquid mixtures were performed at 0.9 mole fraction of water.

Super RLuc8-sFv; a new luciferase-labeled probe for detection of human CD4+ cells

A probe has been designed, produced and assayed for the detection of T-helper cells. The sFv fragment fused to the C-terminus of super Renilla luciferase 8 (Super RLuc8) and the probe successfully used for detection of human CD4+ cells using luminometer.

Olfactory function after nasal plastic surgery

OBJECTIVE

Nasal plastic surgery is a common procedure, which may cause complications. Many patients are concerned about possible changes in the ability to smell. This study aimed to investigate the impact of nasal surgery, by itself, on the sense of smell in a group of patients with minimal endonasal pathologies and no pre-operative olfactory alterations.

METHODOLOGY

In this prospective study from January 2009 until January 2011, we evaluated post-rhinoplasty olfactory changes in a series of 100 rhinoplasty candidates. Olfactory evaluation was performed both subjectively and objectively. The subjective evaluation contained a 0-to-100 Visual Analogue Scale and a five-choice qualitative questionnaire; while, the objective evaluation was performed using the same odor variant of the University of Pennsylvania Smell Identification Test (UPSIT40). Then, the results were analyzed by age, sex, operation method, symptoms, and time-interval groups.

RESULTS

Subjective and objective scoring revealed no significant change in terms of postsurgical olfactory outcome. According to subjective grading, 26 patients had improvement, 61 had no change, and 13 had deterioration of the smell sense. Closed rhinoplasty resulted in a better smell outcome after surgery according to the Visual Analogue Quantitative Score (P = 0.034).

CONCLUSION

Rhinoplasty does not appear to significantly change the preexisting olfactory status.

Transient threshold shift after gunshot noise exposure

BACKGROUND

Many people, such as soldiers, are routinely exposed to gunshot noise during target practice. It is suspected that this high-intensity noise may affect audition through repeated Transient Threshold Shifts (TTS); it can also mechanically alter auditory components such as waves. This study investigates the scope of gunshot noise from the AK-47 rifle (Kalashnikov) and the impact on the shooters' audition.

METHODS

Forty soldiers (80 ears) were recruited in this study. They were all young and being exposed to gunshot noise for the first time. Gunshot characteristics were measured before exposure. The soldiers underwent auditory evaluation with Pure Tone Audiometry (PTA) and Oto-Acoustic Emission (OAE) once before exposure and immediately (less than one hour) after exposure.

RESULTS

The AK-47 gunshot noise pressure level varied between L(AIm) = 73.7 dBA to L(AIm) = 111.4 dBA. Fourteen participants had subclinical hearing impairment in their pre-exposure evaluation; this number increased to 16 after the exposure. Six months post-exposure and later, the number of cases with impairment had fallen to eight (improvement in 50%). Both pre- and post-exposure OAE results were within normal values, while PTA results indicated a significant threshold alteration only at 6 kHz.

CONCLUSION

The results of this study confirm that exposure to gunshot noise with no ear protection can represent a significant hazard for auditory function, especially at higher frequencies.

Postrhinoplasty acne formation: a case-control study

BACKGROUND

Acne formation is a common dermatological problem which, if left untreated, may lead to severe facial scars, a consideration that may be particularly important for patients who seek cosmetic surgery. Postrhinoplasty acne development has not yet been discussed in the literature. We therefore decided to evaluate the occurrence of acne in nasal plastic surgery in a case-control study.

SUBJECTS & METHODS

One hundred and twenty patients were selected for this case-control study and were then assigned to case and control groups, each consisting of 60 patients. None of the participants was a known case of acne and those with any specific skin condition were excluded from the study. The cases were patients whose external nasal structures had been affected by the procedure; the control group consisted of matched patients who were candidates for closed septoplasty. After the operation, acne formation was evaluated in all participants and a comparison was made between cases and controls looking at the surgical method employed, and at the patients' personal and family backgrounds.

RESULTS

Twelve patients, all from the case group, developed postsurgical acne; all these patients had undergone open rhinoplasty. Age, gender, family history for acne and recent medication use prior to the surgery showed no significant correlation with acne formation.

CONCLUSION

The incidence of acne after nasal plastic surgery was significantly higher than in the control group, especially when the method of surgery was open rhinoplasty.

Impact of anti-tuberculosis therapy on plasma zinc status in childhood tuberculosis

This study compared plasma zinc levels in 15 children with active pulmonary tuberculosis, 15 malnourished children and 15 healthy children. Mean plasma zinc concentrations in children with tuberculosis (71.7 microg/dL) were not significantly different than the other 2 groups (72.5 and 76.9 microg/dL). The zinc status of the children with tuberculosis was evaluated after 2 months and 4 months of DOTS therapy. The serum zinc level during anti-tuberculosis therapy decreased after 1 month and then recovered to the initial level after 4 months of treatment.

Efficient electrocatalysis of L-cysteine oxidation at carbon ionic liquid electrode

The electrochemistry of L-cysteine (CySH) in neutral aqueous media was investigated using carbon ionic liquid electrode (CILE). Comparative experiments were carried out using glassy carbon electrodes. At CILE, highly reproducible and well-defined cyclic voltammograms were obtained for l-cysteine with a peak potential of 0.49V vs Ag/AgCl, showing that CILE manifests a good electrocatalytic activity toward oxidation of l-cysteine. A linear dynamic range of 2-210microM with an experimental detection limit of 2microM was obtained. The method was successfully applied to the determination of l-cysteine in a sample of soya milk. Cysteine oxidation at CILE does not result in deactivation of the electrode surface. Mechanistic studies showed that, at CILE, the overall CySH oxidation is controlled by the oxidation of the CyS(-) electroactive species.

Dynamic method as a simple approach for wide range pH measurements using optodes

In this paper, a flow system equipped with an optode has been suggested for wide range pH measurements. Triacetyl cellulose was used as the optode membrane in which different pH indicators were immobilized. For extending the pH range, the dynamic response rather than the steady-state response of the optode was measured. Since diffusion is the main process governing the system response, different parameters having influence on diffusion of the analyte into the membrane were optimized. Under the optimum conditions, wide range pH determination (up to 11 pH units) is simply achieved regardless of the pKa of the pH indicator immobilized in the membrane. To validate the application of the method different indicators with different structures and pKa values were tested and the results were all confirming the precision and accuracy of the method. The suggested method also has combined advantages of flow systems together with inherent advantages of kinetic systems.

Primary and acquired drug resistance in childhood tuberculosis

This study determined the resistance pattern of Mycobacterium tuberculosis to 4 first-line anti-tuberculosis drugs in children with pulmonary tuberculosis at the Iranian National Research Institute of Tuberculosis and Lung Diseases from 1999 to 2004. There were 350 children with positive cultures over the study period: 7 (2%) were resistant to at least one of the 4 anti-tuberculosis drugs. Primary resistance was detected in 4 cases and secondary resistance in 3 cases. Most cases (6) were among Afghan refugees. Resistance to rifampicin both in primary and secondary resistances was high, showing that children in the Islamic Republic of Iran face the threat of drug-resistant tuberculosis transmission.

CCD camera full range pH sensor array

Changes in colors of an array of optical sensors that responds in full pH range were recorded using a CCD camera. The data of the camera were transferred to the computer through a capture card. Simple software was written to read the specific color of each sensor. In order to associate sensor array responses with pH values, a number of different mathematics and chemometrics methods were investigated and compared. The results show that the use of "Microsoft Excel's Solver" provides results which are in very good agreement with those obtained with chemometric methods such as artificial neural network (ANN) and partial least square (PLS) methods.

Simultaneous spectrophotometric determination of Fe(III), Al(III) and Cu(II) by partial least-squares calibration method

A spectrophotometric method for simultaneous determination of Fe(III), Al(III) and Cu(II) using Alizarin Red S as a chelating agent was developed. The parameters controlling behavior of the system were investigated and optimum conditions were selected. A partial least-squares multivariate calibration method was used for the analysis of ternary mixtures of Fe(III), Al(III) and Cu(II) over the range of 450-6000, 140-4000 and 450-15000 ng ml(-1), respectively. Absorbance data were taken between 400 and 800 nm. Applying this method to simultaneous determination of these metal ions in several synthetic alloy solutions with total relative standard error of less than 5% validated the proposed method.

Flow injection analysis of riboflavin with chemiluminescence detection using a N-halo compounds-luminol system

A chemiluminescent method for the determination of riboflavin is described. The method is based on the chemiluminescence (CL) generated during the oxidation of luminol by N-bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) in alkaline medium. It was found that riboflavin could greatly enhance this CL intensity when present in the luminol solution. Based on this observation, a new flow-injection CL method for the determination of riboflavin is proposed in this paper. The detection limits were 7.5 ng/mL and 3.5 ng/mL of riboflavin for the NBS- and NCS-luminol CL systems, respectively. The relative CL intensity was linear, with riboflavin concentration in the range 19-600 ng/mL and 600-2000 ng/mL for the NBS-luminol CL system, and 12-200 ng/mL and 200-2000 ng/mL for the NCS-luminol CL system. The results obtained for the assay of pharmaceutical preparations compared well with those obtained by the official method and demonstrated good accuracy and precision.

Cloud point extraction, preconcentration and simultaneous spectrophotometric determination of nickel and cobalt in water samples

Cloud point extraction has been used for the preconcentration and simultaneous spectrophotometric determination of nickel and cobalt after the formation of a complex with 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA), and latter analysis by spectrophotometer using Triton X-114 as surfactant. The parameters affecting the separation phase and detection process were optimized. Under the optimum experimental conditions (i.e. pH=5, 0.07 mM ACDA, Triton X-114=0.25% (w/v)), calibration graphs were linear in the range of 20-500 and 20-200 microg l(-1) with detection limits of 10 and 7.5 microg l(-1) for Ni and Co, respectively. The method was applied to the determination of Ni and Co in natural and waste water samples with satisfactory results.

Flow-injection determination of isoniazid using sodium dichloroisocyanurate- and trichloroisocyanuric acid-luminol chemiluminescence systems

A chemiluminescent (CL) method for the determination of isoniazid is described. The method is based on the CL generated during the oxidation of luminol by sodium dichloroisocyanurate (SDCC) and trichloroisocyanuric acid (TCCA) in alkaline medium. It was found that isoniazid greatly enhances this CL intensity when present in the luminol solution. Based on this observation, a new flow-injection CL method for the determination of isoniazid has been proposed in this paper. The detection limits were 2 and 3 ng ml(-1) isoniazid for the SDCC-luminol and TCCA-luminol CL systems, respectively. The relative CL intensity was linear with the isoniazid concentration in the range of 4-100 and 100-200 ng ml(-1) for the SDCC-luminol CL system, and 6-200 and 200-1000 ng ml(-1) for the TCCA-luminol CL system. The results obtained for the assay of pharmaceutical preparations compared well with those obtained by the official methods and demonstrated good accuracy and precision.

Sensitive indirect spectrophotometric determination of isoniazid

A simple, rapid, sensitive and accurate indirect spectrophotometric method for the microdetermination of isoniazid (INH) in pure form and pharmaceutical formulations is developed. The procedure is based on the reaction of copper(II) with isoniazid in the presence of neocuproine (NC). In the presence of neocuproine, copper(II) is reduced easily by isoniazid to a Cu(I)-neocuproine complex, which shows an absorption maximum at 454 nm. By measuring the absorbance of the complex at this wavelength, isoniazid can be determined in the range 0.3-3.5 microgml-1. This method was applied to the determination of isoniazid in pharmaceutical formulation and enabled the determination of the isoniazid in microgram quantities (0.3-3.5 microgml-1). The results obtained for the assay of pharmaceutical preparations compared well with those obtained by the official method and demonstrated good accuracy and precision.