Biventricular pacing in the early postoperative period after cardiac surgery.

Cardiac resynchronization therapy is not commonly used in the early postoperative period in patients undergoing cardiac surgery who have left ventricular (LV) dysfunction and a history of heart failure. We performed a prospective randomized clinical trial to compare atrial synchronous right ventricular (DDD RV) and biventricular (DDD BIV) pacing within 72 hours after cardiac surgery in patients with an EF ≤35 %, a QRS interval longer than 120 msec and who had LV dyssynchrony detected by real-time three-dimensional echocardiography (RT3DE). Epicardial pacing was provided by a modified Medtronic INSYNC III pacemaker. An LV epicardial pacing lead was implanted on the latest activated segment of the LV based on RT3DE. The study included 18 patients with ischemic heart disease, with or without valvular heart disease (14 men, 4 women, average age 71 years). Patients undergoing DDD BIV pacing had a statistically significant greater CO and CI (CO 6.7±1.8 l/min, CI 3.4±0.7 l/min/m(2)) than patients undergoing DDD RV pacing (CO 5.5±1.4 l/min, CI 2.8±0.7 l/min/m(2)), p<0.001. DDD BIV pacing in the early postoperative period after cardiac surgery corrects LV dyssynchrony and has better hemodynamic results than DDD RV pacing.

Contact-independent cytotoxicity of Trichomonas vaginalis.

OBJECTIVE: To test the dependency of haemolytic and cytocidal manifestations of pathogenicity of Trichomonas vaginalis on direct contact between the target cells and the organism. TEST ORGANISM: T vaginalis strain Baltimore 42. DESIGN: Haemolysis in the presence of live T vaginalis and of its filter-sterilised metabolic products was compared. The dependence of haemolytic and cytocidal effects on retention of low pH of metabolic products of the organism was demonstrated by parallel titrations of sterile filtrates in normal saline and in phosphate buffered saline (PBS) pH 7.0. RESULTS: Near complete lysis was obtained when erythrocytes mixed with T vaginalis were incubated for 1 h at 37 degrees C in saline containing 1% glucose. The same degree of haemolysis was present in filter-sterilised glucose-saline in which the organism was incubated (1 h/37 degrees C) before erythrocytes were added and incubated under the same conditions as in the mixture with the organism. The degree of haemolysis in filtrates was dependent on retention of low pH (below 5.0) of the suspending fluid in which the organism alone was incubated. Dilution of filtrates in PBS, as opposed to normal saline, abolished or diminished the haemolytic effect. Presence of glucose (energy source) in the saline during incubation of the organism had a pronounced enhancing effect. The production of haemolytic metabolites was temperature dependent, whereas the haemolytic process per se was not. The effect was not an exclusive property of T vaginalis since it was also demonstrated with other trichomonads. The same filtrates applied to tissue culture exerted cytocidal effect strikingly similar to that observed in the haemolysis experiments. CONCLUSION: Neither haemolytic nor cytocidal effect of T vaginalis was contact-dependent.

Acquisition and retention of viruses by Trichomonas vaginalis.

Recently described occurrence of virus-like particles (VLP) in some strains of Trichomonas vaginalis suggests the possibility that the pathogenic significance of this organism may be broadened by its potential for viral transmission. Inasmuch as neither the source nor the host range of the VLP are known, any hazard which they may present for man cannot be estimated. A model has been established for the study of acquisition of known human viruses by T vaginalis. Tissue cultures were infected with two reoviruses and a fresh isolate of genital herpes simplex virus (HSV). A squirrel monkey reovirus was also included in the study. T vaginalis was inoculated into the virus cultures three days later. The progress of virus acquisition by the trichomonads was monitored by transmission electron microscopy and by culture. Virus-containing cell fragments were engulfed by trichomonads and internalised in vacuoles. After digestion of cellular debris only virus particle aggregates were retained. Viable reoviruses were recovered from the trichomonads for nine days, and HSV for six days. The results suggest the possibility of transmission of at least some viruses by T vaginalis.

Basic properties of Tritrichomonas mobilensis hemagglutinin.

Tritrichomonas mobilensis is a recently described enteric protozoon of squirrel monkeys. An earlier report identified one of the metabolic products of this organism as a lectinlike hemagglutinin. Its further properties were determined in this study. Culture supernatants of T. mobilensis FP4190 were concentrated by ultrafiltration through a membrane with 100,000-molecular-weight cutoff. High titers of agglutinin against human erythrocytes were obtained. Incubation at 70 degrees C for 15 min resulted in complete inactivation. Exposure to 56 degrees C for 30 min was without effect, and only partial loss of activity was obtained during incubation for up to 18 h. Maintenance at pH 4 to 9 for 4 h at room temperature had no deleterious effect. Apparent degradation of the hemagglutinin was achieved by 18 h of contact with proteinase K, but trypsin and collagenase were essentially ineffective. Papain increased the sensitivity of the test. In the presence of this enzyme hemagglutinin was demonstrated also in cultures of Tritrichomonas foetus and Tritrichomonas augusta but not in those of Pentatrichomonas hominis or Trichomonas vaginalis.

Detection of hemagglutinins in cultures of squirrel monkey intestinal trichomonads.

Intestinal trichomonads are very common inhabitants of captive squirrel monkeys. In evaluating the potential pathogenicity of these organisms, we encountered hitherto unknown hemagglutinins in their culture fluids. The cytopathic effect associated with a number of the isolates resembled that caused by vacuolating viruses. We have ruled out conventional viruses as the cause of the cytopathic effect and as the source of the hemagglutinin. The agglutinin has some of the basic characteristics of lectins. Parallel experiments demonstrated agglutination of erythrocytes from squirrel monkeys, humans, dogs, cats, guinea pigs, and horses, with the first two types being the most sensitive. Relatively less agglutination was seen with rat erythrocytes. Agglutination of sheep, rabbit, chicken, and bovine erythrocytes was virtually absent.

Growth and cytopathogenicity of Trichomonas vaginalis in tissue cultures.

The primary purpose of this study was to identify the mammalian tissue cultures which were most suitable for investigations of the cytopathogenicity of Trichomonas vaginalis. A recently isolated strain of the organism was inoculated into 15 different tissue cultures which were maintained in an appropriately modified growth medium. Proliferation of the protozoon was accompanied by the progressive disintegration of cell culture monolayers. Initial focal lesions consisting of detached cells and an accumulation of trichomonads gradually enlarged until the entire monolayer was disrupted. When judged by the size of the inoculum required to obtain this effect, differences among the tissue cultures were noted. An inoculum of approximately 10(3) viable trichomonads was sufficient to completely disrupt monolayers of HeLa 229, HeLa, McCoy, HEp-2, and RK-13 cells. To obtain a comparable effect with other cells, 10- to 100-fold higher levels of inoculum were required. Polyethylene glycol concentrates from culture filtrates contained a cell-detaching factor (CDF) which caused detachment and clumping of susceptible cells. Freshly seeded cells in growth medium containing CDF failed to form a monolayer. Aggregates of cells maintained for up to 1 week in the presence of CDF remained viable and formed a monolayer after being washed and suspended in normal growth medium. The activity of the CDF was not lost during 1 week of contact with the cells. The CDF may contribute to the pathogenicity mechanisms of T. vaginalis.

Detection and cultivation of intestinal trichomonads of squirrel monkeys (Saimiri sciureus).

Routine examinations of fecal samples from squirrel monkeys suggested that intestinal trichomonads might be common inhabitants of these animals. In pursuit of these observations, microscopic examination of fecal suspensions and cultures have demonstrated a 100% incidence of trichomonads in 30 arbitrarily selected animals from a colony of more than 300 housed in groups of ten. The most prominent species was Pentatrichomonas hominis. A not yet fully characterized tritrichomonad was also found on several occasions. The main obstacle in establishing individual strains in culture was the presence of bacterial and fungal flora in the samples. Nevertheless, abundant cultures were obtained from 28 animals by inoculation of fecal suspensions into tissue cultures with appropriately formulated medium and high concentration of antibiotics. In several unattended cultures maintained at room temperature, the flagellates retained motility for at least 4 months. This long survival may explain the widespread occurrence of the parasites within a confined animal community.