P-aminosalicylate Research Articles

Characterization of Graft Copolymers Synthesized from p-Aminosalicylate Functionalized Monomeric Choline Ionic Liquid.

An ionic liquid based on the monomeric choline, specifically [2-(methacryloyloxy)ethyl]-trimethylammonium chloride (TMAMA), underwent biofunctionalization through an ion exchange reaction with the model drug anion: p-aminosalicylate (PAS), a primary antibiotic for tuberculosis treatment. This modified biocompatible IL monomer (TMAMA/PAS) was subsequently copolymerized with methyl methacrylate (MMA) to directly synthesize the well-defined graft conjugates with regulated content of ionic fraction with PAS anions (up to 49%), acting as drug delivery systems. The length of the polymeric side chains was assessed by the monomer conversions, yielding a degree of polymerization ranging from 12 to 89. The density of side chains was controlled by "grafting from" using the multifunctional macroinitiators. In vitro drug release, triggered by the ion exchange between the pharmaceutical and phosphate anions in a PBS medium, occurred in the range of 71-100% (2.8-9.8 μg/mL). Owing to significant drug content and consistent release profiles, these particular graft copolymers, derived from biomodified IL monomers with ionically attached pharmaceutical PAS in the side chains, are recognized as potentially effective drug delivery vehicles.

Chelation Combination-A Strategy to Mitigate the Neurotoxicity of Manganese, Iron, and Copper?

The chelating thiol dimercaptosuccinate (DMSA) and the traditional agent D-penicillamine (PSH) are effective in enhancing the urinary excretion of copper (Cu) and lead (Pb) in poisoned individuals. However, DMSA, PSH, EDTA (ethylenediamine tetraacetate), and deferoxamine (DFOA) are water-soluble agents with limited access to the central nervous system (CNS). Strategies for mobilization of metals such as manganese (Mn), iron (Fe), and Cu from brain deposits may require the combined use of two agents: one water-soluble agent to remove circulating metal into urine, in addition to an adjuvant shuttler to facilitate the brain-to-blood mobilization. The present review discusses the chemical basis of metal chelation and the ligand exchange of metal ions. To obtain increased excretion of Mn, Cu, and Fe, early experiences showed promising results for CaEDTA, PSH, and DFOA, respectively. Recent experiments have indicated that p-amino salicylate (PAS) plus CaEDTA may be a useful combination to remove Mn from binding sites in CNS, while the deferasirox-DFOA and the tetrathiomolybdate-DMSA combinations may be preferable to promote mobilization of Fe and Cu, respectively, from the CNS. Further research is requested to explore benefits of chelator combinations.

Analysis of efficacy and safety of linezolid-based chemotherapeutic regimens for patients with postoperative multidrug-resistant spinal tuberculosis

ObjectivesThe study aimed to explore the efficacy and safety of linezolid-based chemotherapeutic regimens for patients with postoperative multidrug-resistant spinal tuberculosis. MethodsThe randomized controlled study included 50 Mycobacterium tuberculosis culture or pathological-confirmed multidrug resistant tuberculosis patients who received spinal surgery from January 2018 to February 2020. Twenty-five patients were assigned to the control group and the study group, respectively. Random number method was used for patient allocation and they were treated with levofloxacin, pyrazinamide, thioisonicotinamide enteric-coated tablet, amikacin sulfate injection, and sodium p-amino salicylate injection, accompanied by linezolid or not. ResultsThe overall effective rate of the study group was higher than that of the control group (88.00% vs 64.00%, P<0.05). The severity of pain at 3 and 6 months postoperatively was lower in the study group than that in the control group (P<0.05). Postoperatively, the study group had higher bone graft fusion rate, shorter mean bone graft fusion time, and higher paraspinal cyst absorption rate than the control group (P<0.05). Postoperatively, the study group had lower levels of PCT, ESR, and CRP than the control group (P <0.05). All patients had normal hepatic and renal function, and no statistical difference of adverse effects between 2 groups were found. ConclusionsLinezolid-based chemotherapeutic regimens can effectively treat patients with postoperative multidrug-resistant spinal tuberculosis but have higher rates of adverse reactions.

Biological In Vitro Evaluation of PIL Graft Conjugates: Cytotoxicity Characteristics.

In vitro cytotoxicity of polymer-carriers, which in the side chains contain the cholinum ionic liquid units with chloride (Cl) or pharmaceutical anions dedicated for antituberculosis therapy, i.e., p-aminosalicylate (PAS) and clavulanate (CLV), was investigated. The carriers and drug conjugates were examined, in the concentration range of 3.125–100 μg/mL, against human bronchial epithelial cells (BEAS-2B) and adenocarcinomic human alveolar basal epithelial cells (A549) as an experimental model cancer cell line possibly coexisting in tuberculosis. The cytotoxicity was evaluated by MTT test and confluency index, as well as by the cytometric analyses, including Annexin-V FITC apoptosis assay. The polymer systems showed supporting activity towards the normal cells and no tumor progress, especially at the highest concentration (100 μg/mL). The analysis of cell death did not show meaningful changes in the case of the BEAS-2B, whereas in the A549 cell line, the cytostatic activity was observed, especially for the drug-free carriers, causing death in up to 80% of cells. This can be regulated by the polymer structure, including the content of cationic units, side-chain length and density, as well as the type and content of pharmaceutical anions. The results of MTT tests, confluency, as well as cytometric analyses, distinguished the polymer systems with Cl/PAS/CLV containing 26% of grafting degree and 43% of ionic units or 46% of grafting degree and 18% of ionic units as the optimal systems.

Synthesis and Characterization of Ionic Graft Copolymers: Introduction and In Vitro Release of Antibacterial Drug by Anion Exchange.

Amphiphilic graft copolymers based on [2-(methacryloyloxy)ethyl]trimethyl- ammonium chloride (TMAMA) were obtained for the delivery of pharmaceutical ionic drugs, such as p-aminosalicylate (PAS) and clavunate (CLV) anions. The side chains were attached by grafting from a multifunctional macroinitiator via atom transfer radical polymerization (ATRP) to get polymers with different grafting degrees and ionic content. The self-assembling ability, confirmed by determining the critical micelle concentration (CMC) through interfacial tension (IFT) with the use of goniometry, was reduced after ion exchange (CMC twice higher than for chloride anions contained copolymers 0.005–0.026 mg/mL). Similarly, the hydrophilicity level (adjusted by the content of ionic fraction) evaluated by the water contact angle (WCA) of the polymer film surfaces was decreased with the increase of trimethylammonium units (68°–44°) and after introduction of pharmaceutical anions. The exchange of Cl− onto PAS− and CLV− in the polymer matrix was yielded at 31%–64% and 79%–100%, respectively. The exchange onto phosphate anions to release the drug was carried out (PAS: 20%–42%, 3.1–8.8 μg/mL; CLV: 25%–73%, 11–31 μg/mL from 1 mg of drug conjugates). Because of the bacteriostatic activity of PAS and the support of the action of the antibiotics by CLV, the designed water-soluble systems could be alternatives for the treatment of bacterial infections, including pneumonia and tuberculosis.

Tuberculosis: are we making it incurable?

Tuberculosis (TB) is most probably the disease that has caused more damage to the human species throughout its history in terms of number of patients and, above all, death toll. There have been thousands of years spent fighting against Mycobacterium tuberculosis in which the human species could only rely on the efficiency of the immune system [1]. We must recall its importance as, in the pre-antibiotic era, the immune system alone could ensure important achievements such as: 1) only 50% of the people exposed to M. tuberculosis contract the infection [2]); 2) only 10% of those infected progress to active disease; and 3) up to 30% of patients with advanced TB disease heal spontaneously (fig. 1]) [3, 4]. In spite of this, the fate of TB patients in the pre-chemotherapy period was very bleak, with a mortality of >50% within 5 years after the onset of disease [3, 4]. For centuries, several empirical treatments were attempted to trying to change this fateful prognosis. Additionally, sanatoriums were built throughout the world for many decades (fig. 2]). However, all these interventions were not really effective, and none of them contributed significantly to improve the doom of TB patients [4]. Then, fortunately, their fate changed dramatically with the advent of the antibiotic era. The two decades from the discovery of streptomycin in 1943 to that of rifampicin in 1963 changed a devastating disease into a relatively easy to cure one. Not only were up to 11 different drugs with activity against M. tuberculosis discovered (streptomycin, p-aminosalicylate (PAS), thiacetazone, isoniazid (H), pyrazinamide, cycloserine, kanamycin, ethionamide, ethambutol, capreomycin and rifampicin (R)), but, based on multiple randomised clinical trials, the basic fundamentals of TB treatment were also established [4, 5 …

Knocking out salicylate biosynthesis genes in Mycobacterium smegmatis induces hypersensitivity to p-aminosalicylate (PAS)

Because of the emergence of strains of Mycobacterium tuberculosis resistant to first-line antituberculosis agents, one of the second-line drugs, p-aminosalicylate (PAS), has regained importance in the treatment of tuberculosis. The mode of action of PAS, however, remains controversial as to whether it inhibits mycobactin or folate biosynthesis. To unravel this, we have studied the effect of PAS on wild-type Mycobacterium smegmatis and its mutants (gene knockouts of the salicylate pathway -trpE2, entC and entD). The wild type had no sensitivity to PAS (MIC>400 μg mL(-1) ), whereas the mutants were hypersensitive, with 1 μg mL(-1) inhibiting growth. The sulphonamides, trimethoprim and dapsone, had little effect on the growth of either the mutants or the wild type. In addition, PAS at 0.5 μg mL(-1) increased the accumulation of salicylate with the wild type and mutants. These results support our hypothesis that PAS targets the conversion of salicylate to mycobactin, thus preventing iron acquisition from the host.

Biochemical characteristics amongMycobacterium bovisBCG substrains

In order to evaluate the biochemical characteristics of 14 substrains of Mycobacterium bovis bacillus Calmette Guérin (BCG) - Russia, Moreau, Japan, Sweden, Birkhaug, Danish, Glaxo, Mexico, Tice, Connaught, Montreal, Phipps, Australia and Pasteur - we performed eight different biochemical tests, including those for nitrate reduction, catalase, niacin accumulation, urease, Tween 80 hydrolysis, pyrazinamidase, p-amino salicylate degradation and resistance to thiophene 2-carboxylic acid hydrazide. Catalase activities of the substrains were all low. Data for nitrate reduction, niacin accumulation, Tween 80 hydrolysis, susceptibility to hydrogen peroxide and nitrate, and optimal pH for growth were all variable among these substrains. These findings suggest that the heterogeneities of biochemical characteristics are relevant to the differences in resistance of BCG substrains to environmental stress. The study also contributes to the re-evaluation of BCG substrains for use as vaccines.

In vivo and in vitro metabolism of aromatic amines in transgenic mice with liver‐selective expression of human arylamine N‐acetyltransferase NAT2

To aid studies into the role of liver‐selective expression of human arylamine N‐acetyltransferase NAT2 in tissue patterns of aromatic amine toxicity, we developed a transgenic mouse line that expresses human NAT2 selectively in liver by linking the human NAT2 protein‐coding exon to the mouse albumin promoter, injecting the transgene into mouse oocytes, and testing offspring for transgene incorporation by Southern blotting. We obtained one transgenic founder that possesses a single copy of the human NAT2 coding region. Transgenic animals and offspring of matings with Nat1/Nat2 null mice were assayed for human NAT2 expression using the human NAT2‐selective substrate sulfamethazine (SMZ) and the NAT1‐selective substrate p‐aminosalicylate (PAS) in in vitro enzyme assays and in vivo plasma pharmacokinetic studies. SMZ‐NAT activity was present in liver cytosols from transgenic animals at levels comparable to those observed in livers from human NAT2 rapid acetylators, while activity was absent in Nat1/Nat2 null controls. Activity in colon was low and that in other tissues was undetectable. SMZ was more efficiently cleared in vivo by human NAT2 transgenic mice than non‐transgenics, while the clearance of PAS was similar between the strains. These mice will be a valuable tool to investigate the importance of liver NAT2 expression in the metabolism and toxicity of aromatic amines in humans.

Generation and functional characterization of arylamine N-acetyltransferase Nat1/Nat2 double-knockout mice.

Arylamine N-acetyltransferases (NATs) catalyze the biotransformation of a variety of arylamine drugs and carcinogens and may play diametrically opposing roles in enhancing either the detoxification of these chemicals or their metabolic activation into DNA-binding electrophiles. To facilitate the study of these processes, we have generated a Nat1/Nat2 double-knockout mouse model by gene targeting in embryonic stem cells. Nat1/2(-/-) mice were born at the expected frequency and seemed normal and viable with no overt phenotype, indicating that these genes are not critical for development or physiological homeostasis. In wild-type mice, NAT1 and NAT2 transcripts were detectable by RT-PCR in all tissues assayed including liver, kidney, colon, brain, bladder, and spleen. NAT1 and NAT2 transcripts were completely undetectable in the Nat1/2(-/-) mice. The in vitro N-acetylation of p-aminosalicylate was detected at significant levels in liver and kidney cytosols from either wild-type inbred 'rapid acetylator' C57BL/6 mice or from outbred CD-1 mice possessing homozygous rapid, heterozygous, or homozygous 'slow acetylator' Nat2 genotypes. Activity was undetectable in cytosol preparations from Nat1/2(-/-) mice. Nat1/2(-/-) mice also displayed severely compromised in vivo pharmacokinetics of p-aminosalicylate (PAS) and sulfamethazine (SMZ), with a drastically increased plasma area under the curve for PAS and a complete absence of their acetylated metabolites (AcPAS or AcSMZ) from plasma, confirming the functional absence of these enzymes and impaired drug metabolism capacity. This knockout mouse model should be helpful in delineating the role that variation in acetylating enzymes plays in mediating interindividual differences in susceptibility to arylamine-induced chemical toxicity and/or carcinogenesis.

Salicylate reduces susceptibility of Mycobacterium tuberculosis to multiple antituberculosis drugs.

Salicylate induces multiple antibiotic resistance in various bacterial species. Here we investigated the effect of salicylate on the susceptibility of Mycobacterium tuberculosis to a range of antituberculosis (anti-TB) drugs. In the presence of salicylate, the killing effects of isoniazid (INH), rifampin (RMP), ethambutol (EMB), streptomycin (STR), and p-aminosalicylate (PAS) were reduced, as shown with a tetrazolium redox dye viability assay and a bacterial survival assay. Salicylate-induced resistance was more pronounced for PAS, STR, and EMB but was not apparent for INH and RMP when salicylate and the anti-TB agents were incorporated into 7H11 plates. The significance of these findings for TB treatment needs to be further evaluated in vivo.

Determination of Diffusion Coefficients of Sodium p-aminosalicylate in Sheep Nasal Mucosae and Dialysis Membranes by Fourier Transform Infrared Horizontal Attenuated Total Reflectance Spectroscopy

Fourier transform infrared horizontal attentuated total reflectance (FT-IR-H-ATR) spectroscopy was employed to determine the diffusion coefficients of sodium p-aminosalicylate (PAS) in sheep nasal mucosae and dialysis membranes. The system configuration, which comprises a closed system with an aqueous layer and a membrane layer, represents diffusion from a solution of limited volume. Data analysis involved fitting a truncated (seven term) Fourier series to the total mass transport into the membrane as a function of time. Comparison of diffusion coefficients of PAS in dialysis membranes obtained by this technique to those obtained by a standard steady-state permeation method showed excellent agreement. Apparent diffusion coefficients were ∼4.33 (±0.38)× 10−7 and ∼9.62 (±5.30) ×10−7 cm2/s for dialysis membranes and sheep nasal mucosae, respectively. These values are substantially smaller than the diffusion coefficient of PAS in aqueous solution, indicating that the rate-limiting step was diffusion in the membrane. The effect of purified gastric mucin solution (concentration up to ∼6% w/v) on the apparent diffusion coefficient of PAS in the membranes was also investigated. The results showed no statistically significant change in the apparent diffusion coefficient in the presence of mucin for either sheep nasal mucosae or dialysis membranes. Although it was reported that mucin in solution retards the diffusion of PAS as compared to buffer alone, the mass transport within the membrane was the rate-limiting step for this hydrophilic compound.

Inhibition of the gastrointestinal absorption of p-aminosalicylate (PAS) in rats and humans by diphenhydramine.

Injection of diphenhydramine, 25 mg per kilogram, intraperitoneally, decreased the blood concentration of sodium p‐aminosalicylate (PAS), 200 mg per kilogram, administered per os. This effect was observed 10,20,30,45, and 60 minutes after administration of PAS. A dose‐response study (2 to 25 mg per kilogram) revealed that the effect was proportional to the dose of diphenhydramine. The decrease in blood concentration of PAS was associated with a similar decrease in the PAS levels in brain, lung, liver, lipids, muscle, and kidney of animals treated with diphenhydramine. PAS levels in the stomach after diphenhydramine, revealed that more than 20% of the PAS remained in the stomach 45 minutes after oral administration but only 3% remained in the stomach in the control animals. Study of the gastrointestinal peristalsis with 51Cr indicated that, 45 minutes after injection of diphenhydramine, 60% of the radioactive marker was found in the stomach, whereas less than 10% was recovered in the stomach of control rats in which most of 51Cr was located in the first segment of the ileum. Human volunteers treated with diphenhydramine, 50 mg intramuscularly, 10 minutes before ingestion of PAS, 2 gm, had significantly less PAS in the blood 10 minutes after ingestion. These observations indicate the importance of the gastrointestinal tract as a site of drug interaction.

Base composition and column chromatography studies of ribonucleic acid differentially extracted from pea roots with sodium lauryl sulfate or p-amino salicylate

Three-day-old pea roots, aseptically grown, were incubated for 2 hr in 32P phosphate and extracted by the phenol method in the absence of sodium lauryl sulfate or p-amino salicylate. One or the other of these compounds was then added and the residue was re-extracted. RNA obtained by the re-extraction with either compound was of higher specific activity and contained a higher mole percent AMP than the RNA from the first extraction. A small part of the AMP-rich RNA eluted with DNA during chromatography on methylated albumin kieselguhr columns, but most of it adhered to the columns. Presence of unlabelled carrier nucleic acids had no measurable effect on the elution pattern.

DISAPPEARANCE OF WAXY EXUDATES IN DIABETIC RETINOPATHY DURING ADMINSTRATION OF P-AMINO-SALICYLATE (PAS).

DISAPPEARANCE OF WAXY EXUDATES IN DIABETIC RETINOPATHY DURING ADMINSTRATION OF P-AMINO-SALICYLATE (PAS).

Further mutational studies on the PAS resistance of Mycobacterium tuberculosis var. hominis.

SUMMARY: Mutational studies on the PAS (sodium p-aminosalicylate) resistance of Mycobacterium tuberculosis var. hominis, strain H37RV have been carried out. It has been assumed that one type of population structure of clones with relation to drug resistance corresponds to one genotype. Clones derived from single colonies obtained on different PAS concentrations produced three types of population structure; the first type is similar to the population structure of the parent strain which has not been previously exposed to the drug and its degree of resistance is up to 0·2 μg. PAS/ml. The second and the third types are different from the parent strain and their degrees of resistance are up to 3 and 1000 μg. PAS/ml., respectively. Neither intermediate population structures nor intermediate degrees of resistance were clearly observed. From these results, it may be concluded that there are only two genotypes responsible for PAS resistance, one determining a lower, and the other a higher degree of resistance.

パス中のメタアミノフェノールの比色定量

A new colorimetric method for the determination of m-aminophenol present in sodium p-aminosalicylate (PAS) has been devised. To a neutral solution containing 1mg. PAS and less than 50 γ of m-aminophenol in 1cc. of solution are added 0.2cc. of 27% ammonia water and 0.6cc. of 35% formaldehyde solution and, after about 5 minutes, 0.1cc. of quinone imide reagent (0.1% butanolic solution of 2, 6-dichloroquinone monochlorimide) is added. This mixture is diluted with distilled water to 5cc., shaken thoroughly and allowed to stand for 1.5hours. The extinction of this colored solution at 590 mμ is measured. The concentration of m-aminophenol in the sample solution is obtained by comparison with the extinction of a standard solution of PAS and m-aminophenol. When the amount of m-aminophenol in the sample is less than 5 γ against 1mg. of PAS, the sample solution is so adjusted as to contain 10mg. of PAS in 1cc. of solntion. In this case, 1.4cc. of formaldehyde solution is used, instead of 0.6cc., to minimize the effet of PAS on the coloration of m-aminophenol.