Prevalence of a postoperative troponin leak in patients with cardiac risk factors undergoing knee and hip arthroplasty in a South African population.

BACKGROUND: Patients undergoing arthroplasty may have comorbidities that put them at risk of myocardial injury after non-cardiac surgery (MINS). MINS, a new clinical concept that has a different pathophysiology from conventional myocardial infarction, is related to a supply-demand mismatch ischaemia in the perioperative setting. MINS is often a silent event, and the diagnosis relies on cardiac biomarker testing such as troponin T. The incidence is estimated at 40%, with a fourfold increase in morbidity and mortality risk 1 year post surgery. OBJECTIVES: To determine the prevalence of postoperative troponin leak in a single-centre arthroplasty unit in patients with various cardiac risk factors undergoing hip or knee arthroplasty and investigate the differences in troponin T levels between comorbidities and different types of arthroplasty, i.e. total hip replacement (THR), total knee replacement (TKR) and neck of femur (NoF) fracture hip replacement. METHODS: A prospective, cross-sectional study of patients with one or more cardiac risk factors undergoing replacement surgery was conducted from October 2017 to April 2018. Troponin levels of all included patients were recorded on days 1 and 3 post surgery using a high-sensitivity cardiac troponin T assay (Roche hs-cTnT). A level of >15 ng/L is considered abnormal and termed a positive troponin leak, while >100 ng/L is considered suspected acute coronary syndrome (ACS). RESULTS: One hundred and sixty patients (n=66 THR, n=55 NoF hip replacement, n=39 TKR) were included. Sixty-eight patients (42%) had a positive troponin leak, and in 6 of these cases ACS was suspected. The highest prevalence of troponin leak was recorded in patients undergoing NoF hip replacement (62%), followed by TKR (46%) and then THR (24%). Sixty-two patients (38%) had positive troponin levels on day 1 and 53 patients (33%) had positive levels on day 3. Important patient cardiac risk factors were identified in the presence of a positive troponin leak, with ischaemic heart disease, hypertension, diabetes, renal disease, age >65 years and atrial fibrillation being statistically most likely. CONCLUSIONS: Postoperative troponin surveillance is an inexpensive and reliable way to identify patients at risk of MINS and subsequently enhance early detection, medical optimisation and referral strategies. Simple interventions may improve outcomes and contribute to lower ACS rates and the timeous prevention of other complications. The prevalence of MINS in orthopaedic-specific patients in South Africa (SA) and other resource-constrained developing countries is unknown. Our finding of 42% positive troponin leaks raises awareness of this issue, and we recommend routine postoperative troponin surveillance for all arthroplasty units in SA.

A multicentre cross-sectional descriptive study evaluating the cardiovascular risk profile of preoperatively identified patients with hypertension.

BACKGROUND: The prevalence of hypertension in adults in South Africa (SA) is 35%. Hypertension is the most important modifiable risk factor for cardiovascular (CV) and chronic kidney disease (CKD) in sub-Saharan Africa. However, 49% of people are unaware of their blood pressure status. Screening for hypertension prior to surgery provides a unique opportunity to diagnose and treat affected individuals. Furthermore, assessing overall CV risk identifies patients at highest risk for complications, and improves the utilisation of scarce resources. OBJECTIVES: To evaluate the CV risk profile of hypertensive patients in the adult population of the Western Cape Province presenting for elective non-cardiac, non-obstetric surgery. METHODS: This report documents the CV risk profile of patients recruited to the HASS-2 study (Hypertension and Surgery Study 2), which was undertaken in seven Western Cape hospitals. Patients were screened for hypertension and pharmacological treatment was initiated or adjusted in patients with stages 1 and 2 disease. Stage 3 patients were referred to a physician. In the present substudy, patients with stages 1 and 2 hypertension were assessed for associated CV risk factors, the presence of target organ damage, and documented CV or kidney disease; they received an overall risk stratification according to the 2018 European Society of Cardiology and the European Society of Hypertension Guidelines. RESULTS: Sixty-one patients with stage 1 and 12 with stage 2 hypertension were analysed. Established CV disease was present in 13.7% of the study population, and CKD (eGFR <60 mL/min) in 10.8%. Seventy-one percent of the study group had a raised body mass index, and 55.9% underlying metabolic syndrome. Prediabetes and diabetes were present in 16.1% and 14.5%, respectively. According to the 2018 European guidelines, 34.7% were at moderate, 33.3% at high and 16.7% at very high risk for a CV event in the following 10 years. CONCLUSIONS: The perioperative period is a critical time during which surgeons, nurses and anaesthetists can influence patients' CV risk of adverse events. This involves appropriate screening, education and treatment. In this study population, nearly 9 out of 10 elective surgical patients with stage 1 or 2 hypertension had CV risk factors placing them at moderate to very high risk. The simultaneous assessment of these additional CV risk parameters, in addition to diagnosis and management of hypertension, may further decrease the health and financial burden in resource-limited facilities in SA, and improve CV outcomes.

Synthesis, characterization, kinetic drug release and anticancer activity of bisphosphonates multi-walled carbon nanotube conjugates.

The statistical proof that most forms of cancer metastasize to bone tissue has redirected research focus to the development of efficient secondary bone cancer treatment regimens. Bisphosphonates (BPs) have been earmarked as a drug of choice for bone metastasis. However, they have a shortcoming of being released before reaching targeted sites due to their low molecular weight. In haste to attain increased efficacy, there is a tendency for drug overdose to occur, resulting in systemic toxicity. One way to curb this is by employing drug delivery systems for targeted and controlled release of the drugs. Having been explored as versatile and innovative drug carriers, multi-walled carbon nanotubes (MWCNTs) have emerged as potential drug delivery systems. Hence, in the present study, alendronate, neridronate and pamidronate are three classes of bisphosphonates that were conjugated onto multi-walled carbon nanotubes. Conjugation was confirmed by characterization techniques including SEM, TEM, EDX, FTIR, Raman and TGA. Drug release studies were also conducted at pH 1.2, 5.5 and 7.4 to study the mechanism of release for neridronate. Results obtained were fitted into Zero order (42.6%), Higuchi (26%) and Korsmeyer-Peppas (22%). The best models describing the release of neridronate from MWCNTs were Zero order, Higuchi and Korsmeyer-Peppas at pH 1.2, 5.5 and 7.4, respectively. A tetrazolium cell viability assay was performed to assess the anticancer activity of the MWCNTs conjugated BPs.

Carbon nanospheres conjugated bisphosphonates: synthesis, characterization and in vitro antimalarial activity.

About 40% of the world's population lives in malaria zones where it presents a challenging health problem. Malaria treatment and prevention have been hindered by drug resistance. Bisphosphonates have been found to be active against Trypanosoma cruzi and Plasmodium falciparum that cause Chaga's disease and malaria respectively. However, bisphosphonates have a shortcoming of being rapidly removed from the bloodstream through the kidneys before reaching the target sites due to their low molecular weight. In the current study, increased bisphosphonates' efficacy for malaria treatment was attempted by conjugating bisphosphonates onto carbon nanospheres (CNSs). The synthesis of the target compounds was confirmed by SEM, TEM, EDX, FTIR, Raman and TGA. The target CNSs containing bisphosphonates were evaluated for antimalarial activity against a chloroquine-resistant strain of P. falciparum. From the free bisphosphonates to the conjugates, the results obtained revealed that there were improvements in percentage parasite kill (from -10.71% to 18%, -18.93% to 28.09% and 10.47% to 28.33% for alendronate, pamidronate and neridronate, respectively). The haemolysis assays revealed that the synthesized compound did not have a toxic impact on healthy red blood cells. The results indicate that bisphosphonates conjugated CNSs are said to be promising P. falciparum blood stage inhibitors.

Plants traditionally used individually and in combination to treat sexually transmitted infections in northern Maputaland, South Africa: antimicrobial activity and cytotoxicity.

ETHNOPHARMACOLOGICAL RELEVANCE: Although medicinal plants are used extensively to treat sexually transmitted infections (STIs) in rural northern Maputaland, KwaZulu-Natal, the efficacy and safety of these plants have not previously been evaluated. AIM OF STUDY: A study was designed to investigate the in vitro antimicrobial activity and cytotoxicity profiles of a selection (individual plants and selected combinations) of traditionally used plants in this study area. MATERIALS AND METHODS: Aqueous and organic (dichloromethane: methanol, 1:1) extracts were prepared. Antimicrobial activity was assessed using the minimum inhibitory concentration (MIC) assay against the STI associated pathogens; Candida albicans ATCC 10231, Ureaplasma urealyticum clinical strain, Oligella ureolytica ATCC 43534, Trichomonas vaginalis clinical strain, Gardnerella vaginalis ATCC 14018 and Neisseria gonorrhoeae ATCC 19424. For the combination study, interactions were assessed using the fractional inhibitory concentration (ΣFIC). The plant species were assessed for safety using the 3-[4,5-dimethyl-2-thiazol-yl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) cellular viability assay on the human embryonic kidney epithelial (Graham, HEK-293) cell line. RESULTS: For the antimicrobial studies, U. urealyticum was the most sensitive of the six test organisms, with the aqueous extract of Ranunculus multifidus (0.02mg/ml) and the organic extract of Peltophorum africanum (0.04mg/ml) being the most antimicrobially active plant species studied. Sclerocarya birrea was found to have the broadest spectrum of activity (mean MIC of 0.89mg/ml). The only plant species to exhibit some degree of cytotoxicity against the kidney epithelial cell line was Kigelia africana (100µg/ml), with 22% and 16% cell death for the aqueous and organic extracts, respectively. Of the 13 combinations studied, several synergistic combinations were evident, the most prominent being the combination of Albizia adianthifolia and Trichilia dregeana (aqueous extract) with an ΣFIC value of 0.15 against O. ureolytica. Synergistic interactions were observed regardless of the ratio of the aqueous mixtures of the two plants. Syzygium cordatum and S. birrea (aqueous extract) was also a combination of interest, demonstrating synergistic (ΣFIC=0.42) interactions against O. ureolytica. This combination, however, also displayed some cytotoxicity towards the human epithelial cell line. CONCLUSION: This study demonstrated that anecdotal evidence of plant use does not always correlate with in vitro activity. Furthermore, the toxicological profiling is of utmost importance as if not combined in its correct ratio can lead to potential adverse effects.

Antimicrobial and antimalarial activity of Cussonia species (Araliaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Cussonia species are used in African traditional medicine mainly against pain, inflammation, gastro-intestinal problems, malaria and sexually transmitted diseases. AIM OF THE STUDY: To summarise ethnomedicinal uses of Cussonia and to find scientific evidence in support of selected main uses. MATERIALS AND METHODS: Using the minimum inhibitory concentration (MIC) method, leaves of 13 Cussonia species, Schefflera umbellifera and Seemannaralia gerrardii were tested against pathogens associated with diarrhoea (Enterococcus faecalis and Escherichia coli), sexually transmitted infections (Neisseria gonorrhoeae and Trichomonas vaginalis) and general infectious diseases (Staphylococcus aureus and Pseudomonas aeruginosa). Antimalarial sensitivity was studied using Plasmodium falciparum and the [(3)H]-hypoxanthine incorporation assay. Cytotoxic effects on a T-cell leukaemia (Jurkat) cell line were determined using the tetrazolium-based cellular toxicity assay. RESULTS: Methanolic extracts were active against Pseudomonas aeruginosa (MIC of 1.0-1.5 mg/mL), Trichomonas vaginalis (MIC of 0.8-1.3 mg/mL) and Staphylococcus aureus (Cussonia arborea, 1.8 mg/mL). All samples were active against Neisseria gonorrhoeae (MIC of 0.02-0.7 mg/mL). The methanol extract of Cussonia arborea was the most active against Plasmodium falciparum (13.68 microg/mL) and showed anticancer properties (5.60 microg/mL). CONCLUSIONS: The traditional use of Cussonia species to treat sexually transmitted diseases and Plasmodium infections appears to have a scientific basis.

Phytochemistry and in vitro pharmacological activities of South African Vitex (Verbenaceae) species.

AIM OF THE STUDY: The in vitro phytochemical and pharmacological investigation of the non-volatile extracts of five South African Vitex species (Verbenaceae); V. obovata ssp. obovata, V. obovata ssp. wilmsii, V. pooara, V. rehmannii and V. zeyheri were investigated in order to validate their traditional use to treat a wide range of ailments such as malaria, wounds, skin diseases and body pains. MATERIAL AND METHODS: The antimicrobial activity was assessed using the minimum inhibitory concentration assay. Through bioactivity-guided fractionation, the fraction responsible for the antimicrobial activity was determined. The toxicity profile, anti-oxidant and anti-inflammatory activity was evaluated using the tetrazolium cellular viability, 2,2-diphenyl-1-picrylhydrazyl and 5-lipoxygenase assays respectively. The antimalarial activity of the extracts and isolated compound from V. rehmannii was also investigated on the chloroquine-resistant Gambian FCR-3 strain of Plasmodium falciparum using the tritiated hypoxanthine incorporation assay. RESULTS: Mostly good antimicrobial inhibition was evident against Gram-positive bacteria (0.02-8.00 mg/ml) and lower activity against the Gram-negative bacteria and the yeast (0.50-8.00 mg/ml). The fraction responsible for antimicrobial activity of V. rehmannii was purified to give a labdane diterpene as an inseparable epimeric mixture of 12S,16S/R-dihydroxy-ent-labda-7,13-dien-15,16-olide. Cirsimaritin was also isolated and identified from V. rehmannii. All the species, apart from V. zeyheri, exhibited scavenging activity (IC50: 22.14+/-1.74 to 33.06+/-1.68 microg/ml) in the anti-oxidant assay. None of the species displayed any anti-inflammatory activity at 100 microg/ml. All the extracts and the labdane diterpene exhibited good antimalarial activity, with the labdane diterpene being the most active (IC50: 2.39+/-0.64 microg/ml). The test extracts were shown to be highly toxic, displaying safety index values ranging from 0.53 to 2.59. CONCLUSION: Of all the pharmacological investigations, the antimalarial and antimicrobial activity exhibited greatest activity and may provide a scientific basis for the ethnomedical use of Vitex species.

The in vitro biological activity of selected South African Commiphora species.

Ten South African Commiphora (Burseraceae) species were investigated to validate their use in traditional healing rites. The leaf and stem extracts of each species were analysed for the anti-oxidant (ABTS and DPPH assays), antimicrobial (MIC and death kinetic assays), anti-inflammatory (5-LOX assay), anticancer (SRB assay) properties, as well as the cytotoxic effects (tetrazolium-based assay). The best anti-oxidant activity (ABTS assay) was observed for the stem extracts of Commiphora tenuipetiolata IC(50)=5.10 microg/ml), Commiphora neglecta (IC(50)=7.28 microg/ml) and Commiphora mollis (IC(50)=8.82 microg/ml). Extracts generally exhibited poor anti-oxidant activity in the DPPH assay, with the exception of Commiphora schimperi (stem), Commiphora neglecta (stem), Commiphora tenuipetiolata (stem and leaf), and Commiphora edulis (stem), with IC(50) values ranging between 7.31 and 10.81 microg/ml. The stem extracts exhibited moderate to good 5-LOX inhibitory activity with Commiphora pyracanthoides (stem) displaying the greatest inhibitory effect (IC(50)=27.86+/-4.45 microg/ml). For the antimicrobial (MIC) assay, a greater selectivity was exhibited by the extracts against the Gram-positive bacteria (0.01-8.00 mg/ml) and the yeasts (0.25-8.00 mg/ml) than against the Gram-negative bacteria (1.00-8.00 mg/ml). Using death kinetic studies (time-kill studies), the rate at which Commiphora marlothii (stem) kills Staphylococcus aureus over a 24h period was determined. Mostly, a concentration-dependent antibacterial activity was observed beginning after ca. 30 min. All concentrations exhibited antibacterial activity, with complete bactericidal effect achieved by the 24(th) hour. The most active Commiphora species against the HT-29 cells (SRB anticancer assay) were Commiphora glandulosa (leaf and stem) and Commiphora marlothii (leaf). The MCF-7 cells (SRB anticancer assay) exhibited the highest sensitivity to indigenous Commiphora species, with Commiphora edulis (leaf and stem), Commiphora glandulosa (leaf and stem), Commiphora marlothii (leaf), Commiphora pyracanthoides (leaf and stem), Commiphora schimperi (stem), and Commiphora viminea (stem) all possessing a percentage inhibition greater than 80% at 100 microg/ml. Commiphora glandulosa (leaf and stem) and Commiphora pyracanthoides (leaf and stem) were the two most active species against the SF-268 cells (SRB anticancer assay), with IC(50) values ranging between 68.55+/-2.01 and 71.45+/-1.24 microg/ml. The majority of the Commiphora extracts were largely non-cytotoxic against Graham human kidney epithelial cells when investigated in the MTT assay.

The in vitro pharmacological activities of 12 South African Hermannia species.

Hermannia species are widely used in traditional medicine in southern Africa, however no extensive study has been conducted on this genus. The acetone extracts of 12 indigenous Hermannia species (flowers, stems and leaves combined) were evaluated for various pharmacological activities. All investigated species displayed promising antimicrobial activity, with Hermannia saccifera being the most active against Staphylococcus aureus (MIC=19.5 microg/ml), Bacillus cereus (MIC=19.5 microg/ml) and Enterococcus faecalis (MIC=125 microg/ml). Time-kill studies on H. saccifera against S. aureus indicated bacteriostatic activity at 1.25, 2.5 and 5.0%, and a concentration of 7.5% achieved complete bactericidal activity after 4h. Ten of the 12 species indicated good free radical scavenging activity, with H. cuneifolia demonstrating the most promising activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH():IC(50)=10.26 microg/ml) and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS(+)/TEAC: IC(50)=10.32 microg/ml) assays. In addition, all species exhibited moderate anti-inflammatory activity in the 5-lipoxygenase assay with the exception of H. cuneifolia (IC(50)=15.32 microg/ml). Overall, the selected species were low in cytotoxicity, except for H. saccifera and H. trifurca. Several Hermannia species indicated promising in vitro biological activity which relate to their traditional use in treating a number of disease states.

The in vitro pharmacological activities and a chemical investigation of three South African Salvia species.

Salvia species (sage) are well known in folk medicine throughout the world. In South Africa sage is used against fever and digestive disorders. Three closely related South African species (Salvia stenophylla, Salvia repens and Salvia runcinata) were investigated for their anti-oxidant (DPPH assay); anti-inflammatory (5-lipoxygenase and cyclo-oxygenase assays); antimalarial (tritiated hypoxanthine incorporation assay); antimicrobial (disc diffusion and micro-dilution assays) properties and toxicity profile (tetrazolium-based assay). The solvent extracts exhibited anti-oxidant, antimalarial and antibacterial and poor anti-inflammatory properties. The essential oils exhibited anti-inflammatory and antimalarial properties, but displayed poor anti-oxidant and antimicrobial activity. The extract of Salviastenophylla and the essential oil of Salvia runcinata displayed the highest toxicity profile. Overall, Salvia runcinata displayed the most favorable activity of all three taxa tested with an IC(50) value of 6.09 (anti-oxidant); 29.05 (antimalarial) and 22.82 microg/ml (anti-inflammatory). Analytical procedures (GC-MS and HPLC-UV) were employed to generate chromatographic profiles for the essential oils and solvent extracts respectively. The HPLC analysis revealed the presence of rosmarinic acid in all three taxa while carnosic acid was only present in Salvia repens and Salvia stenophylla. The GC-MS analysis showed that oils were qualitatively and quantitatively variable. beta-Caryophyllene was present in large amounts in all three taxa. Other components present include camphor, alpha-pinene and alpha-bisabolol. The results of the in vitro pharmacological activities provide a scientific basis to validate the use of these Salvia species in traditional medicine in South Africa.

Structure-activity relationships and inhibitory effects of various purine derivatives on the in vitro growth of Plasmodium falciparum.

The development of novel chemotherapeutic agents has become an urgent task due to the development and rapid spread of drug resistance in Plasmodium falciparum, the protozoan parasite responsible for cerebral malaria. Cyclin-dependent kinases (CDKs) are essential for the regulation of the eukaryotic cell cycle, and several enzymes of this family have been identified in P. falciparum. In recent years, a number of purine-derived kinase inhibitors have been synthesised, some of which display selective activity against CDKs. This report describes a study in which various purine derivatives were screened for in vitro antimalarial activity. The erythrocytic asexual stages of the chloroquine-resistant P. falciparum strain (FCR-3) were cultivated in vitro in the presence of the various purines, and their effect on parasite proliferation was determined by the [3H]hypoxanthine incorporation assay. Our results show considerable variation in the sensitivity of P. falciparum to the different purines, as well as a general independence from their effect on purified starfish CDK1/cyclin B activity, which has been the standard assay used to identify CDK-specific inhibitors. Two subfamilies of purines with moderate to poor activity against CDK1/cyclin B activity showed submicromolar activity against P. falciparum. Structure-activity analysis indicates that certain structural features are associated with increased activity against P. falciparum. These features can be exploited to synthesise compounds with higher activity and specificity towards P. falciparum.

Malaria pigment and extracellular iron. Possible target for iron chelating agents.

Extracellular iron is necessary for many biochemical reactions involved in Plasmodium falciparum growth and multiplication. The incorporation of radioactive iron taken up by the parasite was found, electrophoretically and via gamma counting, to be mainly associated with the haemozoin only in the presence of the active metabolism of the parasite. The potent antimalarial activity of desferrioxamine, a ferric iron chelating agent, has shown that iron deprivation is inhibitory to the parasite. We propose that the mechanism of action of desferrioxamine in addition to the chelation of iron from the parasitic compartment, chelates iron from the haemozoin crystal resulting in free radical generation and parasite death. The ability of desferrioxamine and not the ferrous iron chelating agent, 2,2'-bipyridyl, to chelate the non-haem iron from the haemozoin structure indicates that the oxidative state of iron associated with the haemozoin structure is ferric in nature.

The combined effect of iron chelators and classical antimalarials on the in-vitro growth of Plasmodium falciparum.

The emergence of drug resistant malaria has prompted an intensified search for new antimalarials or combinations of such drugs. Iron chelating agents may represent a new approach to antimalarial treatment and could possibly be used in combination with classical antimalarials. Plasmodium falciparum (FCR-3) strain used at a 1% haematocrit, was subjected to various combinations of the classic antimalarials (chloroquine, pyrimethamine and quinine) and iron chelating agents (desferrioxamine and 2,2'-bipyridyl) in vitro. Tritiated hypoxanthine incorporation was used to determine the growth of the malarial parasites. The iron chelating agents and classic antimalarials when tested alone were found to inhibit the growth of the late stages of the parasite. The combination of the classic antimalarials and iron chelating agents resulted in additive effects on the in-vitro growth of P. falciparum.