SCCmec transformation requires living donor cells in mixed biofilms

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that has emerged through the horizontal acquisition of the staphylococcal cassette chromosome mec (SCCmec). Previously, we showed that SCCmec from heat-killed donors can be transferred via natural transformation in biofilms at frequencies of 10-8-10-7. Here, we show an improved transformation assay of SCCmec with frequencies up to 10-2 using co-cultured biofilms with living donor cells. The Ccr-attB system played an important role in SCCmec transfer, and the deletion of ccrAB recombinase genes reduced the frequency ∼30-fold. SCCmec could be transferred from either MRSA or methicillin-resistant coagulase-negative staphylococci to some methicillin-sensitive S. aureus recipients. In addition, the transformation of other plasmid or chromosomal genes is enhanced by using living donor cells. This study emphasizes the role of natural transformation as an evolutionary ability of S. aureus and in MRSA emergence.

Novel multicellular prokaryote discovered next to an underground stream

A diversity of prokaryotes currently exhibit multicellularity with different generation mechanisms in a variety of contexts of ecology on Earth. In the present study, we report a new type of multicellular bacterium, HS-3, isolated from an underground stream. HS-3 self-organizes its filamentous cells into a layer-structured colony with the properties of a nematic liquid crystal. After maturation, the colony starts to form a semi-closed sphere accommodating clusters of coccobacillus daughter cells and selectively releases them upon contact with water. This is the first report that shows that a liquid-crystal status of cells can support the prokaryotic multicellular behavior. Importantly, the observed behavior of HS-3 suggests that the recurrent intermittent exposure of colonies to water flow in the cave might have been the ecological context that cultivated the evolutionary transition from unicellular to multicellular life. This is the new extant model that underpins theories regarding a role of ecological context in the emergence of multicellularity.

The Use of Autologous 111In-Labelled Platelets and Scintigraphy to Illustrate Enhanced Platelet Activity During Erection in the Chacma Baboon

The demonstration of thrombelastographic hypercoagulability in the penile blood during erection, and the accompanying deposition of fibrin on to the endothelial layer of the deep penile artery and trabecular surface inspired this investigation of the possible role that platelets might play in the process. The blood-pooling pattern in the penis during and after erection from electro-stimulation was studied in 9 male adult baboons (Papio ursinus) using in vivo 99mTc-labelled red blood cells and scintigraphy. Platelet activity was similarly investigated after administering autologous 111In-labelled platelets to the baboons. The results indicate an enhanced platelet concentration with respect to blood-pooling during erection, and an entrapment of platelets after erection.

Radial nerve lacerations--the outcome of end-to-end repairs in penetrating trauma

Due to its mostly motor content, repair of the radial nerve is considered to yield favourable results. This is despite the fact that there are limited studies looking at the outcomes of end-to-end repair secondary to sharp penetrating trauma. We retrospectively reviewed the outcome of a series of repaired level 2 and level 3 radial nerves following penetrating stab injuries. Twenty-seven cases with adequate follow-up were included. All the patients underwent direct end-to-end repair. We evaluated the motor recovery of the target muscles using the British Medical Research Council (MRC) grading system. Wrist extension recovered in 93% of cases at a mean of six months. Finger extension recovered in 74% and thumb extension in 52% of cases within the follow-up period. We conclude that end-to-end repair is possible in the majority of level 2 and level 3 radial nerve lacerations secondary to penetrating stab injuries. Acceptable results can be expected.

A baboon model for in vivo assessment of mucociliary lung clearance

A suitable baboon model (Papio ursinus) for assessing inhibitory effects on mucociliary lung clearance was required. Clearance of various dimensions of nebulized particles (99mTc-labelled) was monitored with the animals (n = 6) under either ketamine or pentobarbitone anaesthesia. The best prospect of substantial and reproducible clearance in spite of the inhibition by the anaesthesia were obtained with pentobarbitone, and using nebulized radiolabelled particles of diameter range between 10 and 45 microns, thus avoiding trapping in the non-ciliary alveoli.

Prostaglandin E1 and papaverine: a comparative study on the ability to increase the penile bloodpool as measured by the 99mTc-penogram in the baboon model

The evaluation of arterial blood supply and venous drainage of the penis is essential in assessing the impotent male. The vaso-active drugs prostaglandin E1 and papaverine, as intracavernous injections, cause penile erections in humans by influencing the arterial blood supply and venous drainage. These drugs were used in the normal baboon and in vascular compromised baboons using a 99mTc-penogram to quantify the vascular status of the penis. Ligation of the A. Iliaca Interna was performed to change the penile blood supply, thus compromising the vascular supply. It was observed that pre- and post-operatively, the increase in the penile bloodpool was more dramatic although not significantly so (P less than 0.05), but more variable after papaverine than with prostaglandin E1. The effect was even more enhanced (P less than 0.05) in the vascular compromised baboons so that the occurrence of priapism after papaverine can speculatively not be excluded. Also the more consistent vasoactive response after prostaglandin E1 seems to establish it as the superior intracavernous injectable agent.

Quantitative evaluation of the penile vascular status by means of the 99mTc-penogram in conjunction with either papaverine or prostaglandin E1 in the anaesthetised baboon model

The evaluation of both the arterial blood supply and the venous drainage of the penis is essential in the assessment of the impotent male. The vasoactive drugs papaverine and prostaglandin E1, as intracavernous injections, cause penile erections by influencing arterial blood supply and venous drainage. These drugs were used in a baboon model together with a 99mTc-penogram to provide information on the vascular status of the penis. An increase in penile blood pool was observed, more dramatic and rapid after administration of papaverine. A quantitative assessment of the vascular status seems possible and will next be monitored in a vascular-compromised baboon for purposes of clinical application.

Investigation by scintigraphic methods of neutrophil kinetics under normal and septic shock conditions in the experimental baboon model

The purpose of this study was the correlation of neutrophil kinetics with the pathogenic course of septic shock in the baboon model. Radioactively labelled neutrophils were traced in vivo in normal baboons (n = 6) and in Escherichia coli-infected baboons, which were reinjected with labelled autologous neutrophils either 2 h after the onset of the E. coli infusion (procedure A) (n = 3) or simultaneously with the infusion (procedure B) (n = 3). Cell isolation was done according to a method developed in this laboratory. The cells were labelled with tropolonate In 111, resuspended in 1-2 ml plasma and reinjected. One-minute images were taken every 5th min and then hourly for 4 h with a gamma camera and analysed with a data processor. Time-activity curves were obtained for neutrophil washout from the lungs and neutrophil accumulation in the liver and spleen. These curves were compared for normal baboons and for those treated according to procedures A and B. A significant retention of neutrophils in the lungs of baboons with E. coli-induced septic shock was noted as well as an abnormally slow rate of accumulation in the liver and spleen. It also seems that any lung injury which could be attributed to changes in neutrophil behaviour should be traced back to events during the early exposure of neutrophils to bacterial infection.

Scintigraphic phase analysis of abnormal A-V conduction in a baboon

During an interventional cardiac investigation on an anaesthetised baboon (Papio ursinus) the animal developed A-V block. Scintigraphic phase analysis leading to quantified intraventricular delays and histogram characteristics pointed to abnormalities which persisted even after A-V block was replaced by nodal tachycardia as was reflected by the electrocardiogram. This indicated towards an increased diagnostic sensitivity with the use of phase analytical methods.

Fourier phase parameters with possible diagnostic importance as obtained from the radionuclide ventriculograms of normal baboons with and without cardiac catheterization and under prolonged anaesthesia

The possible diagnostic importance of parameters defined from radionuclide ventriculograms and Fourier phase analysis was investigated for data from normal baboons (Papio ursinus) under prolonged anaesthesia (7 hours). Of the 14 animals, 7 were studied using indwelling cardiac catheters. Phase angle differences between the electromechanical activation of the septum and left lateral wall (LLW), and again between the activation of the septum and the apex indicated no significant differences (p greater than 0.05) for the consecutive hourly values for both catheterized and non-catheterized baboons. Consequently, average values and their ranges (mean +/- 1 S.D.) were obtained for these parameters in each group, and they did not differ significantly between the two groups. As could be expected, the activation delays between the septum and LLW, and the septum and apex differed with the latter being significantly longer. The phase angle histogram parameters of atrial peak width, left ventricular plus right ventricular peak width, (LV + RV), LV-to-RV peak separation and LV-to-atrial peak separation were similarly analysed and found not to change significantly between hourly measurements or because of catheterization. Therefore mean normal values and ranges were also obtained for these parameters, possibly to serve as baselines in the diagnosis of subtle conduction pathology.

A progressive radiorenographic (99mTc-DTPA) presentation of surgically induced renal vein hypertension in baboons

A 99mTc-DTPA radiorenographic study, supported by excretory urography, blood chemistry and eventually histology was performed on 8 chacma baboons (Papio ursinus) after surgical induction of unilateral renal vein hypertension. Frequent sequential repeat renograms during 6 post-operative months detected fluctuating renal behaviour but did not reveal typical course of the disease. Neither did any one of the radiorenographic parameters (TP, T1/2, FF, relative clearances and perfusion) prove to be more sensitive than the others in detecting abnormalities. Initial microscopic or macroscopic haematuria and proteinuria in general eventually cleared up. Light microscopy demonstrated only mild abnormalities. The effects of venous occlusion of the kidney and the prognosis seemed to be variable as was reflected by radiorenography.

Scintigraphic Phase Analysis of Abnormal A-V Conduction in a Baboon

During an interventional cardiac investigation on an anaesthetised baboon (Papio ursinus) the animal developed A-V block. Scintigraphic phase analysis leading to quantified intraventricular delays and histogram characteristics pointed to abnormalities which persisted even after A-V block was replaced by nodal tachycardia as was reflected by the electrocardiogram. This indicated towards an increased diagnostic sensitivity with the use of phase analytical methods.

Phase mapping from left ventricular radionuclide ventriculograms: interobserver reliability and accuracy of the programme

Phase analysis of data from radionuclide ventriculograms is known to provide space-time information on the mechanical emptying of pixels located in the ventricular regions. It could therefore perhaps be useful for detecting abnormal sequences of contraction of the ventricles as well as to localize sites of premature electromechanical action. The phase programme used in this investigation is designed to trace the electromechanical action of the ventricles from colour-coded phase images (first harmonic Fourier transform), not only visually from a cinematic representation, but particularly from a data output of x, y coordinates and phase angles of sites chosen as they empty in the ventricular regions. Six healthy baboons were subjected to conventional radionuclide ventriculography, performed hourly for the duration of 11 h under anaesthesia. The programme was used by two independent observers to map the progression of emptying for each of the thus acquired 66 left ventricular phase images. The interobserver reliability and the accuracy achieved in mapping normal contraction patterns was found to be good. Abnormalities which appeared during the prolonged anaesthesia and which were confirmed with 12 lead electrocardiography were likewise detected consistently.

The effect of an oral gold preparation on the gastrointestinal tract motility in two species of experimental animals

The oral gold preparation, auranofin, used in rheumatoid arthritis has been reputed to cause chronic diarrhea. To investigate this the G.I. tract motility was measured before auranofin therapy and after 1, 3, and 5 weeks of therapy using scintigraphy following indium-111-labeled meals in three beagle dogs. The gastric emptying times of the dogs accelerated throughout the duration of the experiment, although the large bowel transit times did not seem to be affected. The affect of auranofin on the stools of the baboon Papio ursinus was also noted. The baboon stools were observed for any change in consistency. Sigmoidoscopic examination including mucosal biopsies was carried out monthly over a 6-month period. The baboon's stools were noted to become very soft in consistency, but histology indicated no mucosal changes.

The sensitivity of radionuclide and thermodilution techniques to detect cardiac dysfunction in the baboon model during prolonged anaesthesia

This study was undertaken to evaluate the fluctuations of cardiac parameters in a baboon model during pentobarbitone anaesthesia which will serve as a baseline control for shock studies. Thermodilution and radionuclide methods were used to determine cardiac parameters. Radionuclide studies were repeated without any cardiac catheters to assess the effect of these on cardiac performance. The results represent baseline fluctuations in cardiac parameters against which cardiac dysfunction can be diagnosed in shock studies. The results also indicate that cardiac catheterisation does not affect cardiac performance significantly.

The Sensitivity of Radionuclide and Thermodilution Techniques to Detect Cardiac Dysfunction in the Baboon Model During Prolonged Anaesthesia

This study was undertaken to evaluate the fluctuations of cardiac parameters in a baboon model during pentobarbitone anaesthesia which will serve as a baseline control for shock studies. Thermodilution and radionuclide methods were used to determine cardiac parameters. Radionuclide studies were repeated without any cardiac catheters to assess the effect of these on cardiac performance. The results represent baseline fluctuations in cardiac parameters against which cardiac dysfunction can be diagnosed in shock studies. The results also indicate that cardiac catheterisation does not affect cardiac performance significantly.

Entrapment of platelets in the penis during and after erection

Because of the development of hypercoagulability and the deposition of fibrin in the penis during erection a study of the possible role of platelets in this process was undertaken. Platelet response was studied in 9 adult chacma baboons (Papio ursinus) using autologous in vitro indium-111-labelled platelets and sequential scintigraphy of the penis during erection. The blood pooling pattern was obtained using in vivo technetium-99m-labelled red cells in a similar investigation. A statistically significant retention of platelets occurred during and after erection, which could not be attributed to blood pooling (P less than 0,05). Entrapment of platelets could lead to enhanced activity and activation, and might play a significant role in hypercoagulability and fibrin deposition during erection. Therefore platelets could be an important factor in the pathogenesis of ageing impotence.

A comparison of 111In-labelled polymer beads and 99mTc-Sn-colloid as solid food and semi-solid food tracers for scintigraphic gastric emptying studies

In order to establish the efficacy of labelling a solid meal and a semi-solid meal with either 111In-labelled polymer beads or 99mTc-tin colloid beagle dogs were fed variously labelled meals of different consistencies and then monitored by scintigraphy for gastric motility patterns. The labelling with each tracer was either performed by thoroughly mixing it into the food before cooking, or alternatively by surface labelling after the food had been cooked. For the 99mTc-Sn-colloid tracer no difference was found in the measured gastric emptying times resulting from either pre-cooking labelling or surface labelling of the meals. Cooking the tracer together with the ingredients does however seem to promote a firm entrapment of the 111In-polymer beads into a solid protein, and in this manner the 111In-labelled resin appears to be a reliable solid food tracer. Surface labelling with 111In-polymer beads of a solid meal with a smooth texture fails totally and the tracer empties with the liquid phase.

The detection and evaluation of drug-induced changes in the gastrointestinal motility of beagle dogs using a 111In-labelled resin mixed into a standard meal as tracer

An investigation was performed to establish the usefulness of 111In-labelled polymer beads mixed into a standard meal as a tracer of gastrointestinal(GI)-motility changes due to the influence of various drugs. The labelled polymer beads were well mixed into the food, which was then fed to healthy beagle dogs undergoing drug therapy. GI motility was monitored using a gamma camera and data processor. The results were compared to those obtained from corresponding placebo studies on the same dogs. A significant acceleration of gastric emptying and colon transit was noted under the influence of a gastric and intestinal prokinetic coded R51619. No influence on GI motility could, however, be detected after the administration of a calcium-blocking agent to the dogs.

The use of autologous 111In-labelled platelets and scintigraphy to illustrate enhanced platelet activity during erection in the chacma baboon

The demonstration of thrombelastographic hypercoagulability in the penile blood during erection, and the accompanying deposition of fibrin onto the endothelial layer of the deep penile artery and trabecular surface inspired this investigation of the possible role that platelets might play in the process. The bloodpooling pattern in the penis during and after erection from electro-stimulation was studied in 9 male adult baboons (Papio ursinus) using in vivo 99mTc-labelled red blood cells and scintigraphy. Platelet activity was similarly investigated after administering autologous 111In-labelled platelets to the baboons. The results indicate an enhanced platelet concentration with respect to bloodpooling during erection, and an entrapment of platelets after erection.

Detection of abscesses and lymphosarcoma with 111In-deferoxamine mesylate

Indium-111 deferoxamine was used to delineate induced abscesses or different ages in a baboon, and lymph nodes in a case of canine spontaneous lymphosarcoma, by means of gamma-scintigraphy. Positive results were obtained already 1 hr after administration of the scanning agent, and the lesion-to-background ratio improved progressively with time. The tissue distribution of the radiopharmaceutical was determined in rats, and showed a relatively high isotope retention in the kidneys.

Detection of Abscesses and Lymphosarcoma with 111In-Deferoxamine Mesylate

Indium-111-deferoxamin wurde zum Nachweis sowohl induzierter Abszesse unterschiedlichen Alters in einem Pavian als auch der Lymphknoten in einem Fall von spontanem Lymphosarkom bei Hunden mittels Gamma-Szintigraphie nachzuweisen. Positive Resultate wurden bereits 1 Std. nach der Verabreichung erzielt; das Verhältnis von Target zu Hintergrund verbesserte sich ständig im Laufe der Zeit. Die Gewebeverteilung des Radiopharmakons wurde bei Ratten bestimmt und eine relativ hohe Isotopenkonzentration in den Nieren beobachtet.

In vivo nuclear techniques in veterinary medicine

A description is given of the more relevant procedures of diagnostic nuclear medicine as well as of future trends in this field, especially with regard to in vivo research and clinical applications at the biochemical level. The part played by animal models in the past and present is emphasised. The inclusion of a nuclear medicine facility, as equipped and run by the Atomic Energy Board at the H.A. Grové Animal Research Centre is put into perspective.