In vitro toxicity and internalization of gold nanoparticles (AuNPs) in human epithelial colorectal adenocarcinoma (Caco-2) cells and the human skin keratinocyte (HaCaT) cells.

Ingestion and transdermal delivery are two common routes of nanoparticle (NP) exposure. In this study, the intracellular uptake, cytotoxicity and genotoxicity of 14 nm and 20 nm citrate-stabilized gold nanoparticles (AuNPs), 14 nm polyethylene glycol (PEG)-liganded carboxyl AuNPs, 14 nm PEG-liganded hydroxyl AuNPs and 14 nm PEG-liganded amine AuNPs were assessed on human epithelial colorectal adenocarcinoma (Caco-2) cells and the human skin keratinocyte (HaCaT) cells. The uptake of AuNPs in the cells was confirmed through darkfield microscopy and hyperspectral imaging followed by spectral angle mapping (SAM). A high level of citrate AuNPs was found in both cell lines whilst uptake of PEGylated AuNPs was low, irrespective of their functional groups. Cytotoxicity assessed by cell impedance was only observed for the 14 nm citrate-stabilized AuNPs. Enhanced cell proliferation was also observed in 14 nm PEG-liganded hydroxyl and 14 nm PEG-liganded amine AuNP-treated Caco-2 and HaCaT cells. For the assessment of genotoxicity, the in vitro micronucleus assay was used. Dose-dependent genotoxicity was observed in both Caco-2 and HaCaT cells, with all the AuNPs inducing genotoxicity. In conclusion, the entry of NPs into the cells as well as toxicity was dependent on their physicochemical properties such as surface coating and different chemical functional groups.

Hydrolysis of nitriles by soil bacteria: variation with soil origin.

AIMS: The aim of this study was to explore bacterial soil diversity for nitrile biocatalysts, in particular, those for hydrolysis of ß-substituted nitriles, to the corresponding carboxamides and acids that may be incorporated into peptidomimetics. To achieve this, we needed to compare the efficiency of isolation methods and determine the influence of land use and geographical origin of the soil sample. METHODS AND RESULTS: Nitrile-utilizing bacteria were isolated from various soil environments across a 1000 km long transect of South Africa, including agricultural soil, a gold mine tailing dam and uncultivated soil. The substrate profile of these isolates was determined through element-limited growth studies on seven different aliphatic or aromatic nitriles. A subset of these organisms expressing broad substrate ranges was evaluated for their ability to hydrolyse ß-substituted nitriles (3-amino-3-phenylpropionitrile and 3-hydroxy-4-phenoxybutyronitrile) and the active organisms were found to be Rhodococcus erythropolis from uncultivated soil and Rhodococcus rhodochrous from agricultural soils. CONCLUSIONS: The capacity for hydrolysis of ß-substituted nitriles appears to reside almost exclusively in Rhodococci. Land use has a much greater effect on the biocatalysis substrate profile than geographical location. SIGNIFICANCE AND IMPACT OF THE STUDY: Enzymes are typically substrate specific in their catalytic reactions, and this means that a wide diversity of enzymes is required to provide a comprehensive biocatalysis toolbox. This paper shows that the microbial diversity of nitrile hydrolysis activity can be targeted according to land utilization. Nitrile biocatalysis is a green chemical method for the enzymatic production of amides and carboxylic acids that has industrial applications, such as in the synthesis of acrylamide and nicotinamide. The biocatalysts discovered in this study may be applied to the synthesis of peptidomimetics which are an important class of therapeutic compounds.

Characterisation of two bifunctional cellulase-xylanase enzymes isolated from a bovine rumen metagenome library.

Ruminant digestive tract microbes hydrolyse plant biomass, and the application of metagenomic techniques can provide good coverage of their glycosyl hydrolase enzymes. A metagenomic library of circa 70,000 fosmids was constructed from bacterial DNA isolated from bovine rumen and subsequently screened for cellulose hydrolysing activities on a CMC agar medium. Two clones were selected based on large clearance zones on the CMC agar plates. Following nucleotide sequencing, translational analysis and homology searches, two cellulase encoding genes (cel5A and cel5B) belonging to the glycosyl hydrolyse family 5 were identified. Both genes encoded pre-proteins of about 62 kDa, containing signal leader peptides which could be cleaved to form mature proteins of about 60 kDa. Biochemical characterisation revealed that both enzymes showed alkaline pH optima of 9.0 and the temperature optima of 65 °C. Substrate specificity profiling of the two enzymes using 1,4-ß-D-cello- and xylo-oligosaccharides revealed preference for longer oligosaccharides (n ≥ 3) for both enzymes, suggesting that they are endo-cellulases/xylanases. The bifunctional properties of the two identified enzymes render them potentially useful in degrading the ß-1,4 bonds of both the cellulose and hemicellulose polymers.

Evidence of a long QT founder gene with varying phenotypic expression in South African families.

We report five South African families of northern European descent (pedigrees 161, 162, 163, 164, and 166) in whom Romano-Ward long QT syndrome (LQT) segregates. The disease mapped to a group of linked markers on chromosome 11p15.5, with maximum combined two point lod scores, all generated at theta = 0, of 15.43 for the D11S922, 10.51 for the D11S1318, and 14.29 for the tyrosine hydroxylase (TH) loci. Recent studies have shown that LQT is caused by an Ala212Val mutation in a potassium channel gene (KVLQT1) in pedigrees 161 to 164. We report that the same mutation is responsible for the disease in pedigree 166. Haplotype construction showed that all the families shared a common haplotype, suggesting a founder gene effect. DNA based identification of gene carriers allowed assessment of the clinical spectrum of LQT. The QTc interval was significantly shorter in both carriers and non-carriers in pedigree 161 (0.48 s and 0.39 s, respectively) than the same two groups in pedigree 161 (0.52 s and 0.42 s, respectively). The spectrum of clinical symptoms appeared more severe in pedigree 162. The possible influence of modulating genetic factors, such as HLA status and sex of family members, on the expression of an LQT founder gene is discussed.

[An electroglottographical analysis of certain voice parameters: normative indications]. / 'N elektroglottografiese analise van sekere stemparameters: normatiewe aanduidings.

A comprehensive voice evaluation comprises more than just the evaluation of perceptual and organic aspects. Objective voice analysis should supplement the diagnostic battery. In order to obtain normative indications for the Speech Research Laboratory at the University of Pretoria, 25 men and 25 women ranging in age from 8 to 80 years and with perceptually normal voices were tested with regard to fundamental frequency, cycle to cycle frequency fluctuation (jitter), cycle to cycle amplitude fluctuation (shimmer) and harmonic/noise ratio. Results indicate that these parameters are sensitive to changes in voice production caused by ageing, changes in loudness and the production of different vowels. The implications of these results for research and clinical practice are discussed.

Psychotherapeutic approach to the management of the severely injured patient.

In this modern day and age, severe injury has become the dire consequence of an ever-increasing number of motor vehicle, industrial and mining accidents as well as sport-, military- and terror-related incidents that occur. The management of the severely injured patient is mostly directed on an exclusively physical level. Often, very little attention is afforded to the psychosocial factors that prevail following physical trauma. The author describes and discusses how holistic multidisciplinary intervention within the medical milieu facilitates a more psychotherapeutic approach to the management of severely injured patients. This approach facilitates physical recovery and increases the rate of readjustment and reintegration into society, of those who have sustained severe injury.

Sudden cardiac death during ambulatory ECG monitoring. A report of 2 cases.

Two cases of sudden cardiac death during ambulatory ECG monitoring, each with an episode of torsade de pointes as part of the terminal dysrhythmia, are reported. In the first case, pause-dependent changes of the TU waves favour early after-depolarisations and triggered activity as the initiating mechanism of torsade. Quinidine therapy was probably an aggravating factor. Torsade was not initiated in a pause-dependent fashion in the second patient, who had ECG evidence of an episode of ischaemia as trigger for the terminal dysrhythmia. Both patients had impaired left ventricular function and underlying coronary artery disease.

Intravenous streptokinase in acute myocardial infarction.

The safety and efficacy of streptokinase (STK) (Kabikinase; Keatings) in restoring vessel patency in 70 patients with acute myocardial infarction are reported. Return of vessel patency occurred more frequently (76%) in patients receiving STK than in patients in a control group (12%) (P = 0.001). The main complication was bleeding, which invariably resulted from invasive procedures. Dangerous dysrhythmias were uncommon and no fatalities were caused by STK administration. It is recommended that thrombolytic therapy be started as early as possible in patients with acute myocardial infarction, who can then be referred to centres equipped for coronary angiography for further management. Unnecessary invasive procedures should be avoided.

The prevalence of rheumatoid arthritis in a rural African population.

We report the findings of an epidemiological study of the prevalence of rheumatoid arthritis (RA) in a rural population. The study was conducted in Venda, a very remote part of South Africa. Much of the population still follows an age old traditional lifestyle. A detailed hut-to-hut survey of 543 respondents comprising 97% of the population of one village was conducted. This included clinical, serological and radiological studies. This was supplemented by questioning local traditional doctors and showing them photographs of typical hand deformities to ascertain if they knew of any cases with these deformities. The 3 hospitals draining the area were also surveyed. The detailed survey of 543 respondents revealed no cases of definite or probable RA using a modification of the Rome criteria. No cases were recognized by the traditional doctors. The 3 hospitals together had 14 cases of definite RA out of a population of about 520,000. This gave a prevalence of 0.0026%. The marked difference in the prevalence of RA in this population as opposed to other Southern African studies as well as American and European studies is discussed.

The efficacy of alternative routes for the infection or vaccination of animals with Cowdria ruminantium.

The efficacy of subcutaneous, intramuscular and intraperitoneal inoculation of heartwater infective blood or nymph suspensions was tested in 5 experiments involving a total of 199 sheep. The success rate of subcutaneous injections varied greatly (0-100%) in the different groups. However, it was found that certain additives to the inoculum, such as dimethyl sulphoxide or uninfective brain tissue, increased the efficacy of the subcutaneous route. Indications are that the site of inoculation and especially the dose volume are important factors in the success rate of such inoculations. Intramuscular injection with infective nymph suspensions containing bradikynin or hyaluronidase produced heartwater reactions in 11 out of 14 sheep. In 2 experiments, involving 25 cattle, it was found that, although very few animals showed definite reactions after the subcutaneous or intramuscular injection of nymph suspension and additives, the majority were afterwards immune to challenge. This phenomenon, which was also present in some sheep, needs further investigation.