[Digestive complications of aspirin]

Stem cell therapy as a promising approach for ischemic stroke treatment

Ischemia as the most common type of stroke is the main cause of death and disability in the world. However, there are few therapeutic approaches to treat ischemic stroke. The common approach to the treatment of ischemia includes surgery-cum-chemical drugs. Surgery and chemical drugs are used to remove blood clots to prevent the deterioration of the nervous system. Given the surgical hazards and the challenges associated with chemical drugs, these cannot be considered safe approaches to the treatment of brain ischemia. Besides surgery-cum-chemical drugs, different types of stem cells including mesenchymal stem cells and neurological stem cells have been considered to treat ischemic stroke. Therapeutic approaches utilizing stem cells to treat strokes are promising because of their neuroprotective and regenerative benefits. However, the mechanisms by which the transplanted stem cells perform their precisely actions are unknown. The purpose of this study is to critically review stem cell-based therapeutic approaches for ischemia along with related challenges.

Safety of surfactant excipients in oral drug formulations

Surfactants are a diverse group of compounds that share the capacity to adsorb at the boundary between distinct phases of matter. They are used as pharmaceutical excipients, food additives, emulsifiers in cosmetics, and as household/industrial detergents. This review outlines the interaction of surfactant-type excipients present in oral pharmaceutical dosage forms with the intestinal epithelium of the gastrointestinal (GI) tract. Many surfactants permitted for human consumption in oral products reduce intestinal epithelial cell viability in vitro and alter barrier integrity in epithelial cell monolayers, isolated GI tissue mucosae, and in animal models. This suggests a degree of mis-match for predicting safety issues in humans from such models. Recent controversial preclinical research also infers that some widely used emulsifiers used in oral products may be linked to ulcerative colitis, some metabolic disorders, and cancers. We review a wide range of surfactant excipients in oral dosage forms regarding their interactions with the GI tract. Safety data is reviewed across in vitro, ex vivo, pre-clinical animal, and human studies. The factors that may mitigate against some of the potentially abrasive effects of surfactants on GI epithelia observed in pre-clinical studies are summarised. We conclude with a perspective on the overall safety of surfactants in oral pharmaceutical dosage forms, which has relevance for delivery system development.

A Review on Medicinal Plants Used in the Management of Headache in Africa

The use of medicinal plants in the management of diverse ailments is entrenched in the culture of indigenous people in African communities. This review provides a critical appraisal of the ethnobotanical uses of medicinal plants for the management of headache in Africa. Research articles published from 2010 (Jan) to 2021 (July) with keywords such as Africa, ethnobotany, headache, medicinal plant and traditional medicine were assessed for eligibility based on sets of pre-defined criteria. A total of 117 plants, representing 56 families, were documented from the 87 eligible studies. Asteraceae (10%), Fabaceae (10%), Lamiaceae (9%) and Mimosaceae (5%) were the most represented plant families. The most popular plant species used in the management of headache were Ocimum gratissimum L. (n = 7), Allium sativum L. (n = 3), Ricinus communis L. (n = 3) and Artemisia afra Jack. ex. Wild (n = 2). The leaves (49%), roots (20%) and bark (12%) were the most common plant parts used. Decoction (40%) and infusion (16%) were the preferred methods of preparation, whereas the oral route (52%) was the most preferred route of administration. The data revealed that medicinal plants continue to play vital roles in the management of headache in African communities. In an attempt to fully explore the benefits from the therapeutic potential of indigenous flora for common ailments, further studies are essential to generate empirical evidence on their efficacies, using appropriate test systems/models. This approach may assist with the ongoing drive towards the integration of African traditional medicine within mainstream healthcare systems.

Association of bowel movement frequency and laxative use with risk of hepatocellular carcinoma in US women and men

Abnormal bowel movements have been related to a variety of hepatocellular carcinoma (HCC) risk factors such as dyslipidemia, diabetes and altered metabolism of bile acids and gut microbiota. However, little is known about whether bowel movement frequency affects the risk of developing HCC. We followed 88 123 women in the Nurses' Health Study (NHS) and 28 824 men in the Health Professionals Follow-up Study (HPFS) for up to 24 years. The Cox proportional hazards regression model was used to calculate multivariable hazard ratios (HRs) and confidence intervals (95%CI). We documented 101 incident HCC cases. Compared to those with daily bowel movements, participants with bowel movement more than once per day had a multivariable HR of 1.93 (95%CI: 1.18 to 3.16) in the pooled cohorts. For the same comparison, the positive association appeared stronger for men (2.72, 95% CI: 1.14 to 6.44) than for women (1.63, 95% CI: 0.87 to 3.06) but there was no statistically significant heterogeneity by sex (P-value = .31). We found null associations between bowel movement every 2 days or less and the risk of HCC (HR = 1.05, 95%CI: 0.62 to 1.79). The HR (95%CI) for participants who used laxatives regularly relative to those who never used laxatives was 1.00 (0.64 to 1.55). Our results suggest participants with bowel movement more than once daily is associated with a higher risk of developing HCC compared to those with daily bowel movements. These findings need to be confirmed and potential mechanisms underlying this association need to be elucidated.

Aspirin is associated with low oral pH levels and antacid helps to increase oral pH

Objective

Aspirin is a commonly used medicine for primary and secondary prevention of cardiovascular diseases. It is an acidic medicine associated with gastric irritation and acid reflux, which in turn can lead to low oral pH levels. Therefore, it is important to understand the association between aspirin and oral pH levels in order to achieve an optimum oral health condition among patients who take aspirin on prescription.

Results

Out of 373 patients, 162 (44%) were males and 245 (66%) were on aspirin. 71% of aspirin taking patients and 29% of non-aspirin taking patients had oral pH less than 6.5 (P < 0.01). Aspirin showed a significant association with low oral pH levels (odds ratio = 1.91, 95% CI 1.23–2.99, P < 0.01). 78 patients were given antacids and followed up for 4 weeks, 63 of them (81%) showed an improvement in oral pH and the improvement was marked in the group who had oral pH between 5.5–6.0 compared to the group who had oral pH between 6.0–6.5 (P = 0.03). The results show that aspirin therapy is associated with low oral pH and administration of an antacid with aspirin helps to increase the oral pH level.

The oriented processes for extraction and recovery of paracetamol compound across different affinity polymer membranes. Parameters and mechanisms

Membrane processes represent one of the most promising technologies for separation and extraction in modern industries, because they have several advantages. Today these processes are an important research topic, including affinity polymer membranes that are highly efficient for oriented processes. Three affinity polymer membrane types containing lipophilic compounds, methyl cholate (MC) and cholic acid (CA) as extractive agents were prepared and characterized. They have been used to extract active ingredient paracetamol (acetaminophen), from concentrated solutions (0.08-0.01M). Substrate acetaminophen is an important active ingredient and its recovery as a pure compound, is very useful for the pharmaceutical industry. These affinity polymer membranes were adopted to perform experiments on a facilitated extraction process of this substrate at different medium acidities and temperatures. Macroscopic parameters, permeabilities (P) and initial fluxes (J₀) for a facilitated extraction of this substrate through each membrane were determined. The results indicate that values of initial fluxes (J₀) of the extracted substrate are related to its initial concentration C₀ by a saturation law, which allowed to determine microscopic parameters, apparent diffusion coefficients (D^*) and association constants (K_ass) of formed entity (substrate - extractive agent) (ST). The results show a clear influence of temperature and acidity factors on the evolution of these parameters and membrane performances in this studied process. Activation parameters (E_a, ΔH^≠, and ΔS^≠) were determined and the values indicate that high performances of these membrane types are certainly related to the movement nature of the substrate across the organic phase, and the structures of the substrate and the extractive agent.

In silico and In vitro evaluation of the anti-inflammatory potential of Centratherum punctatum Cass-A

Centratherum punctatum Cass., a herb belonging to the family Asteraceae has been traditionally used as a curative against diverse disorders like inflammation, tumor, depression, and hypertension. Though the medicinal properties of this plant have been attributed to the presence of flavonoids, glucosides, alkaloids, Vitamin C, etc., the molecular constituents of this plant and of the flavonoids that contribute to its medicinal activity have not been explored yet. This work attempts to evaluate the potential of Centratherum punctatum extract as an anti-inflammatory agent. Ethanolic extracts of Centratherum punctatum analyzed by High Performance Thin Layer Chromatography (HPTLC) and Liquid Chromatography-Mass Spectrometry (LC-MS/MS) identified the presence of the flavones kaempferol, glycoside Isorhamnetin-3-O-rutinoside, and kaempferol-3-glucoside. The plant extract exhibited anti-oxidant property as confirmed by DPPH assay and IC₅₀ value of 271.6 μg/mL during inhibition of protein denaturation, 186.8 μg/mL during RBC membrane stabilization, and 278.2 μg/mL for proteinase inhibition. Membrane stabilizing functions of flavones and flavones glycosides validated the anti-inflammatory potential of the extract. In silico evaluation using a rigorous molecular docking protocol with receptors of Cox2, TNF-α, Interleukin 1β convertase, and Histamine H1 predicted high binding affinity of the isoflavones and isoflavone glycosides of Centratherum punctatum Cass. The interactions have also been shown to compare well with that of known drugs valdecoxib through Gln178, His342, and Gly340, desloratadine (through Lys191 and Thr194) and belnacasin (through Asp288 and Gly287) proven to function through the anti-inflammatory pathway. This work establishes the anti-inflammatory potential of Centratherum punctatum Cass. extract as an alternative to existing therapeutic approach to inflammation through a systematic in silico approach supplementing the findings.

Reduced mucosal side-effects of acetylsalicylic acid after conjugation with tris-hydroxymethyl-aminomethane. Synthesis and biological evaluation of a new anti-inflammatory compound

Acetylsalicylic acid (ASA) causes adverse haemorrhagic reactions in the upper gastrointestinal (GI) tract, and previous results have suggested that combination therapy with 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) could provide protection in this scenario. Based on this hypothesis, our aim was to develop a new compound from ASA and Tris precursors and to characterize the biological effects of ASA-Tris and the derivatives ASA-bis- and mono-hydroxymethyl-aminomethane (ASA-Bis, ASA-Mono, respectively) using in vivo and in vitro test systems. ASA or ASA conjugates (0.55mmol/kg, each) were administered intragastrically to Sprague-Dawley rats. Changes in the mucosal structure and in the serosal microcirculation were detected by in vivo imaging techniques, the plasma TNF-alpha, tissue xanthine oxidoreductase and myeloperoxidase activities, and liver cytochrome c changes were also determined. In two separate series, platelet aggregation and carrageenan arthritis-induced inflammatory pain were measured in control, ASA and ASA-Tris-treated groups. Severe mucosal injury and a significant decrease in serosal red blood cell velocity developed in the ASA-treated group and an ~2-fold elevation in proinflammatory mediator levels evolved. ASA-Tris did not cause bleeding, microcirculatory dysfunction, mucosal injury or an elevation in proinflammatory markers. The ASA-Mono and ASA-Bis conjugates did not cause macroscopic bleeding, but the inflammatory activation was apparent. ASA-Tris did not influence the cyclooxygenase-induced platelet aggregation significantly, but the inflammatory pain was reduced as effectively as in the case of equimolar ASA doses. ASA-Tris conjugation is an effective approach through which the GI side-effects of ASA are controlled by decreasing the cytokine-mediated progression of pro-inflammatory events.

Colon-targeted delivery of live bacterial cell biotherapeutics including microencapsulated live bacterial cells

There has been an ample interest in delivery of therapeutic molecules using live cells. Oral delivery has been stipulated as best way to deliver live cells to humans for therapy. Colon, in particular, is a part of gastrointestinal (GI) tract that has been proposed to be an oral targeted site. The main objective of these oral therapy procedures is to deliver live cells not only to treat diseases like colorectal cancer, inflammatory bowel disease, and other GI tract diseases like intestinal obstruction and gastritis, but also to deliver therapeutic molecules for overall therapy in various diseases such as renal failure, coronary heart disease, hypertension, and others. This review provides a comprehensive summary of recent advancement in colon targeted live bacterial cell biotherapeutics. Current status of bacterial cell therapy, principles of artificial cells and its potentials in oral delivery of live bacterial cell biotherapeutics for clinical applications as well as biotherapeutic future perspectives are also discussed in our review.

The study of the influence of surfactant charge on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) using spectrophotometric methods

In this research, the effects of micellar systems on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) were found to be dependant upon the surfactant charge within the micelle. In cationic micelles, there is a catalytic effect at low concentrations of surfactant. However, this reaction is inhibited at higher surfactant concentrations. In anionic micelles, a catalytic effect occurs, while in zwitterionic and non-ionic micelles there is an inhibitory effect. Such reactions are attributable to changes in reactants on the micellar surface, or to the fact that both reactants are found in different microenvironments. The pseudophase (PS) and ion-exchange (PPIE) models were found to be consistent with the experimental result. Furthermore, the association constants for both drugs could be determined together with micellar rate constants in heterogeneous media.

[Epidemiology of digestive complications associated with use of low-dose aspirin]

Low-dose aspirin (< 330 mg/d) is recommended for the prevention of myocardial infarction or ischemic stroke. Six to 12% of the general population is exposed to low-dose aspirin. The most frequently studied digestive complications are bleeding peptic ulcers, whose risk is increased twofold by low-dose aspirin treatment, and non-complicated peptic ulcers. History of bleeding or non-complicated peptic ulcer, alcohol intake, concomitant treatment with NSAID or calcic inhibitors are demonstrated risk factors of bleeding ulcer associated with low-dose aspirin. The role of enteric coating, of low-dose aspirin dose, of delay since low-dose aspirin treatment onset, and of Helicobacter pylori infection, remains controversial. Antisecretory drugs (H2 inhibitors, proton pump inhibitors), and nitroglycerin are associated with a decreased risk of bleeding ulcer. The protective effect of COX-2 inhibitors on the risk of bleeding ulcer is suppressed by concomitant treatment with low-dose aspirin. The risk of no- complicated peptic ulcer was increased by low-dose aspirin intake by a factor 2.9 in one study. Low-dose aspirin dose, infection by Helicobacter pylori, NSAID intake, and absence of enteric coating, are possible risk factors for non-complicated peptic ulcer. No association was retrieved with alcohol intake and peptic ulcer history.

Colonic toxicity of administered drugs and chemicals

Although uncommon, medication-induced colonotoxicity is important to recognize because medication cessation generally leads to prompt clinical improvement, while medication continuation results in disease exacerbation. This review categorizes the association between medications and colonotoxicity as "well-established" or "probable," according to the following criteria: total number of reported cases, number of different research groups reporting an association, experimental and pharmacologic evidence of an association, and validity of an association in each reported case. Cocaine, ergotamine, estrogen, sodium polystyrene, alosetron, amphetamines, pseudoephedrine, and vasopressin are associated with colonic ischemia. The mechanisms include vasospasm, thrombogenesis, and shunting of blood from mesenteric vessels. Narcotics, phenothiazines, vincristine, atropine, nifedipine, and tricyclic antidepressants are associated with colonic pseudo-obstruction. The mechanisms include antagonizing prokinetic neurotransmitters, stimulating antikinetic neurotransmitters, promoting dysmotility, relaxing smooth muscle, and injuring enteric neurons. Numerous antibiotics are associated with pseudomembranous colitis; ampicillin is associated with hemorrhagic colitis; chemotherapy is associated with neutropenic colitis; and deferoxamine is associated with Yersinia enterocolitis. Mechanisms of these toxicities include altering normal bowel flora, weakening immunologic defenses, promoting microorganism virulence, and mucosal injury. Gold compounds, nonsteroidal antiinflammatory drugs, alpha-methyldopa, salicylates, and sulfasalazine are associated with an inflammatory or cytotoxic colitis. The mechanisms include direct mucosal cytotoxicity, antimetabolite effects, or drug allergy. Nonsteroidal antiinflammatory drugs, cyclo 3 fort, flutamide, lansoprazole, and ticlopidine are associated with lymphocytic colitis. The mechanisms include immunologic activation or attenuated immunologic defenses. Chronic cathartic use leads to colonic hypomotility and abdominal distention. Intrarectally administered corrosive compounds can produce a toxic colitis.

Maintaining patency of tunneled hemodialysis catheters--efficacy of aspirin compared to warfarin

OBJECTIVE

Tunneled hemodialysis catheters (caths) often fail as a result of luminal obstructive thrombus or formation of a fibrin sheath at the tip. Anecdotal and non-randomized studies have indicated that aspirin (A) and/or warfarin (W) can prolong cath patency. We examined the effect of chronic usage of either A or W on primary cath patency.

MATERIAL AND METHODS

A prospective cross-sectional monitoring of cath patency was conducted over a 3-year period. Patients were grouped according to their long-term usage of either A (325 mg daily) or W. Patients on neither medication served as a control (C). The end point of the study occurred at cannulation of the patients' arteriovenous fistulae, when there was development of cath-related bacteremia or when there was inability to maintain a blood flow of 250 ml/min.

RESULTS

Sixty-three patients with a mean age of 57 +/- 15 years completed the study. There were 21 patients in the A group, 11 in the W group and 31 in the C group. Cath survival was 91%, 73% and 29% at 120 days for the A, W and C groups, respectively (A vs C, p < 0.0001; W vs C, p < 0.0001; A vs W, p = NS). The mean durations of cath patency were 114 +/- 18, 111 +/- 17 and 68 +/- 37 days for the A, W and C groups, respectively (A vs C, p < 0.0001; W vs C, p < 0.0001; A vs W, p = NS). Gastrointestinal (GI) bleeding complication rates were 24%, 18% and 0% for the A, W and C groups, respectively (A vs C, p = 0.02; W vs C, p = 0.02; A vs W, p = NS). The relative risk of GI bleeding associated with aspirin was 0.71 [95% confidence interval (CI) 0.11-4.4, p = 0.7] but among elderly aspirin users it was 1.14 (CI 1.0-1.3, p = 0.008).

CONCLUSION

Both aspirin and warfarin are equally effective at prolonging cath patency but their routine use for failing caths cannot be unequivocally recommended because of the increased risk of GI bleeding. Further prospective and randomized studies are called for.

[Aspirin throughout the ages: a historical review]

Even at the beginning of the next millennium, aspirin will still offer surprises. Its relatively young pharmacological history compares with the early use of salicylate-containing plants since antiquity. The Assyrians and the Egyptians were aware of the analgesic effects of a decoction of myrtle or willow leaves for joint pains. Hippocrates recommended chewing willow leaves for analgesia in childbirth and the Reverend Edward Stones is acknowledged as the first person to scientifically define the beneficial antipyretic effects of willow bark. At the beginning of the 19th century salicin was extracted from willow bark and purified. Although a French chemist, Charles Gerhardt, was the first to synthesize aspirin in a crude form, the compound was ignored, and later studied by Felix Hoffmann. He reportedly tested the rediscovered agent on himself and on his father, who suffered from chronic arthritis--a legend was born and Bayer Laboratories rose to the heights of the pharmacological world. First used for its potent analgesic, antipyretic and anti-inflammatory properties, aspirin was successfully used as an antithrombotic agent. Sir John Vane elucidated aspirin's active mechanism as an inhibitor of prostaglandin synthetase and received the Nobel Price in Medicine for this work in 1982. Two isoform of cyclooxygenase (COX-1 and COX-2) have now been identified, each possessing similar activities, but differing in characteristic tissue expression. The cox enzyme is now a target of drug interventions against the inflammatory process. After two centuries of evaluation, aspirin remains topical, and new therapeutic indications are increasingly being studied.

[Pharmacology of aspirin]

Aspirin (acetylsalicylic acid) is the best-known salicylate and belongs to the non steroid anti-inflammatory drug class. Despite wide use being made since more than 100 years, knowledge about mechanism of action and therapeutic issues continually evolves. The main mechanism of action is prostaglandin synthesis inhibition. This is achieved through inhibition of prostaglandin endoperoxide synthase (PGHS) or cyclooxygenase (COX) synthesis. Most of the therapeutic uses of aspirin are explained by this mechanism. Nevertheless aspirin uses change as time goes by: if the main one during the first fifty years was an analgesic, anti-pyretic and anti-inflammatory one, the last fifty years saw aspirin being used mainly as an anti-thrombotic agent, in primary and secondary thrombo-embolic prevention. Better knowledge of mechanism of action points today at, on one hand, more selective and therefore better tolerated molecules, and, on the other hand, at new therapeutic applications, such as anti-cancer and neurodegenerative diseases prevention.