The toxic effects on cardiac myocytes of tyledoside F, a cumulative neurotoxic cardiac glycoside isolated from Tylecodon grandiflorus

To investigate the cardiac cellular effects of tyledoside F, a cumulative neurotoxic bufadienolide and ouabain, a non-cumulative cardenolide, the whole-cell clamp method was used to measure the Na-K pump current after the Na-K pump had been activated by high intracellular Na²⁺. The toxic effects of tyledoside F and ouabain on cardiac myocytes were also investigated by observing the effect of the Ca²⁺ overload on the viability of myocytes during a period of 75 min. From the results it is clear that there are similarities in the direct effects of tyledoside F and ouabain on the Na-K pump. It was found that ouabain inhibited the Na-K pump current more than that of tyledoside F. With regard to Ca²⁺ overload, there are differences in their mode of production of Ca²⁺ overload because cinnarizine protects the myocytes against ouabain-induced Ca²⁺ overload but not against tyledoside-induced Ca²⁺ overload. This study shows that with the whole-cell clamp technique tyledoside F inhibited the Na-K pump in a manner similar to inhibition of the pump by ouabain. Viability studies with myocytes indicated that tyledoside F also has other effects which are different from these of ouabain.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Screening of the venoms of two Parabuthus scorpion species on isolated cardiomyocytes

Crude, diluted venoms of Parabuthus transvaalicus and P. granulatus were tested on isolated cardiomyocytes. Ventricular myocytes were subjected to hypercontractility tests and whole-cell voltage clamp. Both venoms had a profound influence on the hypercontractility of cardiomyocytes, which was markedly decreased when they were pre-absorbed with commercial antiserum. Whole-cell clamp results showed an increase in the sodium current, and a retardation of the time course of inactivation, implicating the presence of an a toxin in both venoms.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

A comparison of haemodynamic and vasoconstrictory responses in sheep with a toxic fraction from Pachystigma pygmaeum and with the plant material

ST-segment changes in the ECG, which are an indication of acute myocardial ischaemia, are obtained when a small quantity of an extract from dried Pachystigma pygmaeum is injected intravenously in sheep. When the fraction was injected subcutaneously, animals reached a crisis after about 5 h, with low values of stroke volumes and high values for pulmonary arterial pressures, pulmonary vascular resistances and heart rates. The haemodynamic changes are an indication of the development of pump failure of the heart. In sheep, injected subcutaneously with the toxic fraction, as well as for sheep dosed with plant material through rumen fistula, increased serum levels for thromboxane and increased or decreased levels for prostacycline were observed. The experimental results are interpreted as being an indication that these prostaglandines may be involved in the development of gousiekte by impeding cardiopulmonary function as a result of coronary and pulmonary vasoconstriction. The sudden death observed in some gousiekte sheep may be due to myocardial ischaemia and associated arrhythmias.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Experimental gallop rhythm in sheep with Gousiekte : correlation of changes in amplitude with haemodynamic parameters

To investigate the correlation of haemodynamic parameters with the intensity of the gallop sound (S₃), use was made of right heart catheterization with a Swan-Ganz catheter to measure the pulmonary and right atrial pressures. The cardiac output was determined with the thermodilution method. A radiocardiogram was obtained after a bolus injection of technetium pertechnetate. The cardiopulmonary flow-index was obtained from the simultaneous recordings of the radiocardiogram and an electrocardiogram. With the haemodynamic parameters, heart sounds were recorded simultaneously and externally with a microphone. Eight Merino sheep were dosed with dried Pachystigma pygmaeum (Schltr) Robyns plant material through rumen fistulas until the clinical symptoms of heart failure such as gallop sounds, systolic murmurs and haemodynamic symptoms as well as increases in end diastolic pressure and decreases in stroke volume, appeared. After the appearance of the symptoms the sheep were treated symptomatically to delay the development of the cardiomyopathy. The changes in haemodynamic parameters before and after treatment were used and correlated with the intensity of the gallop sounds on a 6 point criterium scale. The results in brief show that, for gallop sound intensities between 0 and 6 on the criterium scale, most of the haemodynamic parameters correlate with the intensity of the gallop sounds, except the cardiac output, cardiopulmonary blood volume and the systemic and pulmonary vascular resistances. The haemodynamic parameters correlate better with the intensities of the gallop rhythm between 0 and 3. It is evident from this study that the model of heart failure in sheep is useful to study heart sounds and may also be valuable in the study of the genesis of the gallop sound.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Cardiotoxicity of the skin of the red-banded rubber frog, Phrynomerus bifasciatus (Smith 1847)

The skin of the red-banded rubber frog is said to secrete an unidentified toxin. Whole skin extract as well as HPLC fractions were tested for toxicity on viable, isolated cardiomyocytes. The skin extract and one of its fractions were shown to be cardiotoxic. Whole-cell clamping tests demonstrated that both extract and fraction interfered with the function of the potassium channels of the cardiomyocytes and that the toxic substance has an affinity for the IK₁ channels. Investigations are in progress to isolate and characterize the toxic substance.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Medical Research Council. PU for CHE.mn201

Evaluation of waist-to-height ratio to predict 5 year cardiometabolic risk in sub-Saharan African adults

Simple, low-cost central obesity measures may help identify individuals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify individuals with hypertension, pre-diabetes, or dyslipidaemia; 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population; and 3) assess which measure best predicts 5-year CVD riskPeer reviewedFinal Accepted Versio

The effect of three bufadienolide cardiac glycosides on contraction of isolated rat jejunum

Three cardiac glycosides were screened for pharmacological effects on isolated rat jejunum. The contraction of rat jejunum with epoxyscillirosidin, a non-cumulative bufadienolide, and cotyledoside and tyledoside D, both cumulative neurotoxic bufadienolides were compared with methacholine. The results indicate that all three bufadienolides cause contraction of jejunal smooth muscle. When combined with atropine (1X10ˉ⁶ M) the response of epoxyscillirosidin and tyledoside D decreased, indicating suppression of a cholinergic response caused by the cardiac glycosides.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Cardiovascular health screening among South African students

Stress is an unavoidable part of everyday life due to the demands and stressors associated with modern lifestyle. Health risks provoked by this increasingly prevalent condition lead to cardiovascular disease, which ultimately results in a poor health status. Studies have confirmed that there is a correlation between a person’s lifestyle and stress levels: sedentary lifestyles increase the risk of developing various cardiovascular conditions. Improved physical fitness is one of the lifestyle modifications proven to benefit heart health by reducing the effects of stress and its associated threats. The purpose of this study was to compare the heart health of subjects from two further education and training institutes. Institution 1 is a traditional tertiary institution that focuses on lectures, while Institution 2 provides an organised, daily physical training programme in addition to its academic programme. Subjects underwent a non-invasive ViportTM test which measures the cardio stress index (CSI), heart rate (HR), and QRS duration. Additional variables measured included: age, gender, perceived stress level, systolic and diastolic blood pressure and body mass index. Results obtained from the study indicate that students from Institution 1 (n=158) had significantly higher readings (p<0.001) than those from Institution 2 (n=128) on CSI and HR, but significantly lower readings on blood pressure (systolic and diastolic). In theory, this finding may be attributed to the fact that individuals from Institution 1 (training population) follow a set daily physical routine which improves their heart health and decreases stress- related risk.http://www.ajol.info/journal_index.php?jid=153&ab=ajpher

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.SP201