Towards establishing a rhinoceros-specific interferon-gamma (IFN-γ) assay for diagnosis of tuberculosis

Mycobacterium bovis is the causal agent of bovine tuberculosis (BTB), with a diverse host range, extending from livestock to domestic and captive wild animals as well as free-ranging wildlife species. In South Africa, BTB is endemic in the Kruger National Park (KNP) and the Hluluwe iMfolozi National Park (HiP), where the high prevalence of M. bovis infections in buffalo herds has led to infection of a number of wildlife species. This has raised concerns about the spillover into the rhinoceros population, a species known to be susceptible to both M. bovis and Mycobacterium tuberculosis, jeopardizing breeding and relocation projects that serve to conserve and protect this species. In view of the advantages of the interferon-gamma (IFN-γ) assay in the diagnosis of BTB in a variety of species worldwide, such an assay has been developed for rhinoceroses by Morar and co-workers in 2007. In this study, this assay was optimized using recombinant eukaryotic rhinoceros IFN-γ and the lower detection limit was calculated to be 0.5 ng/ml. Subsequently, assessing the detection of native rhinoceros IFN-γ protein in whole-blood samples revealed stimulation with each of the mitogens: pokeweed (PWM), phytohaemagglutinin (PHA) & phorbol 12-myristate 13-acetate and calcium ionophore (PMA/CaI), though most prominently with the latter two. In addition, samples collected from 52 clinically healthy rhinoceroses, of presumed negative BTB status, from two different areas in South Africa were used to determine the cut-off value for a negative test result. This was calculated to be 0.10 (OD490 nm ) and as determined in this study is a preliminary recommendation based on IFN-γ responses observed in samples from BTB-free rhinoceroses only.

Assessment of myocardial performance with ventricular pressure-volume relations: clinical applications in cardiac surgery

The assessment of myocardial performance in patients with cardiomyopathy is of vital importance in cardiology and cardiac surgery, especially considering the significant increase in the number of patients treated for congestive heart failure. Left ventricular pressure-volume analysis is a method, which can assess accurately myocardial contractility, separating the systolic and diastolic function at different preload and afterload conditions. This technique can be used for determination of the efficacy of a therapeutic pharmaceutical or surgical intervention, for instance the assessment of ventricular function after coronary revascularization. A few studies using the conductance catheter for the analysis of ventricular pressure-volume relations in the field of cardiac surgery have been published. In our center we started to use this technique to analyze cardiac surgical procedures, like mitral valve reconstruction, aortic valve replacement, myocardial revascularization, left ventricular assist, and surgical left ventricular remodeling. This information will be used to develop a therapeutic strategy, which may optimize surgical indications and improve the peri- and postoperative treatment and the efficacy of that surgical technique. In this short review the possible clinical use in cardiac surgery and the methodology of the pressure-volume loops have been described. Three clinical cases are presented to demonstrate functional information related to the surgical treatment of congestive heart failure patients.

Cardiomyoplasty--the beginning of a new era

Cardiomyoplasty is a surgical treatment for a well-defined group of patients who suffer from congestive heart failure. The procedure is not a contraindication to perform a future heart transplantation, when indicated. The clinical results up to 7 years after cardiomyoplasty are encouraging, but there is still a gap between the significant functional capacity improvement of the patients after cardiomyoplasty and the moderate hemodynamic change. Experimental data and recent measurements in patients provide new insights in understanding the physiologic effect of cardiomyoplasty.

Contraction-induced movements of water in single fibres of frog skeletal muscle

Although X-ray diffraction measurements imply almost constant filament separation during isometric contraction, such constancy does not hold at the level of the isolated cell; cell cross-section increases substantially during isometric contraction. This expansion could arise from accumulation of water drawn from other fibre regions, or from water drawn into the cell from outside. To distinguish between these hypotheses, we froze single fibres of frog skeletal muscle that were jacketed by a thin layer of water. Frozen fibres were freeze-substituted, sectioned transversely, and examined in the electron microscope. In fibres frozen during contraction, we found large amounts of water just beneath the sarcolemma, less in deeper regions, and almost none in the fibre core. Such gradients were absent or diminished in fibres frozen in the relaxed state. The water was not confined to the myofibril space alone; we found large water spaces between myofibrils, particularly near mitochondria. Accumulation of water between myofibrils and around mitochondria implies that the driving force for water movement probably lies outside the filament lattice, and may therefore be osmotic. The fact that the distribution was nonuniform-highest near the sarcolemma and lowest in the core--implies that the water was likely drawn from the thin jacket surrounding the cell. Thus, the contractile cycle appears to be associated with water entry into and exit from the cell.

Entrapment of tined leads

A rare complication is described, in three patients. The tined tip of a ventricular pacemaker electrode was entrapped in the chordae of the tricuspid valve and could not be removed by subtle manipulations in two patients. In one patient, the electrode was removed with partial rupture of the tricuspid valve. The two electrodes remained in the entrapped position and new electrodes were inserted in all three cases. No clinical sequelae were found during follow-up of at least 24 months.