The C-terminal tail of tetraspanin proteins regulates their intracellular distribution in the parasite Trichomonas vaginalis.

The parasite Trichomonas vaginalis is the causative agent of trichomoniasis, a prevalent sexually transmitted infection. Here, we report the cellular analysis of T.vaginalis tetraspanin family (TvTSPs). This family of membrane proteins has been implicated in cell adhesion, migration and proliferation in vertebrates. We found that the expression of several members of the family is up-regulated upon contact with vaginal ectocervical cells. We demonstrate that most TvTSPs are localized on the surface and intracellular vesicles and that the C-terminal intracellular tails of surface TvTSPs are necessary for proper localization. Analyses of full-length TvTSP8 and a mutant that lacks the C-terminal tail indicates that surface-localized TvTSP8 is involved in parasite aggregation, suggesting a role for this protein in parasite : parasite interaction.

Use of gastric balloon manometry for estimation of intra-abdominal pressure in horses.

REASONS FOR PERFORMING STUDY: Standing laparoscopic procedures, facilitated by abdominal insufflation with carbon dioxide, are being employed to an increasingly greater extent in horses. However, a sustained increase in abdominal pressure may be life-threatening. A practical method for intra-abdominal pressure (IAP) assessment is imperative. Although indirect methods for estimating IAP have been extensively studied in man, little work has been performed in veterinary medicine. OBJECTIVES: To investigate the utility of gastric manometry for purposes of evaluating IAP in horses. METHODS: Gastric pressure (P(ga) ) was estimated by balloon manometry in 8 healthy, mature horses, before and during a 30 min passive pneumoperitoneum induced by right paralumbar puncture. The balloon manometer was positioned within the gastric lumen and inflated using 2 separate volumes of air: 10 and 50 ml. P(ga) Gastric pressure was determined at baseline (0) and 5, 15 and 30 min after induction of passive pneumoperitoneum. Intra-abdominal pressure was measured directly by right paralumbar puncture using an 8 gauge needle at baseline and immediately following establishment of passive pneumoperitoneum. RESULTS: Baseline IAP values were negative and increased (P≤0.05) during development of passive pneumoperitoneum. However, recorded P(ga) measurements for both inflation volumes were positive before (baseline) and during the course of the passive pneumoperitoneum. Measured P(ga) values did not correlate with IAP at any time. CONCLUSIONS AND POTENTIAL RELEVANCE: Our results suggest that the indirect method used in human patients for estimating IAP by P(ga) is not applicable for horses.

Effect of passive pneumoperitoneum on oesophageal pressure, cardiovascular parameters and blood gas analysis in horses.

REASONS FOR PERFORMING STUDY: Standing surgical procedures are being employed to an ever-greater extent in horses. Pneumoperitoneum during abdominal surgery might adversely affect the work of breathing. OBJECTIVES: To determine whether development of pneumoperitoneum during abdominal surgery adversely influences the work of breathing. METHODS: Eight healthy mature horses were equipped with carotid artery and thoracic vena cava catheters and an intraluminal manometry system. The following measurements were obtained before and at +5, +10, +15 and +30 min following establishment of pneumoperitoneum by paralumbar puncture using an 8 gauge needle: vital signs, oesophageal pressure, gastric pressure, arterial and central venous blood pressures, and arterial and mixed venous blood gas analyses. RESULTS: Significant changes in oesophageal pressure, central venous pressure and results of arterial and mixed venous blood gas analysis were not detected. Arterial diastolic and mean pressures and rectal temperature increased slightly (P ≤ 0.05). CONCLUSIONS: Passive pneumoperitoneum did not adversely affect breathing mechanics or haemodynamic variables under experimental conditions. Changes in arterial pressure could have occurred as a response to the passive pneumoperitoneum or be related to handling stress. Subtle variations in rectal temperature were not clinically relevant and likely resulted from stress associated with restraint. POTENTIAL RELEVANCE: It is unlikely that mature horses will develop signs of respiratory difficulty as a result of the development of passive pneumoperitoneum during standing laparoscopy.

Inhibition of polyamine synthesis arrests trichomonad growth and induces destruction of hydrogenosomes.

Trichomonad parasites such as Tritrichomonas foetus produce large amounts of putrescine (1,4-diaminobutane), which is transported out of the cell via an antiport mechanism which results in the uptake of a molecule of spermine. The importance of putrescine to the survival of the parasite and its role in the biology of T. foetus was investigated by use of the putrescine analogue 1, 4-diamino-2-butanone (DAB). Growth of T. foetus in vitro was significantly inhibited by 20 mM DAB, which was reversed by the addition of exogenous 40 mM putrescine. High-performance liquid chromatography analysis of 20 mM DAB-treated T. foetus revealed that putrescine, spermidine, and spermine levels were reduced by 89, 52, and 43%, respectively, compared to those in control cells. The DAB treatment induced several ultrastructural alterations, which were primarily observed in the redox organelles termed hydrogenosomes. These organelles were progressively degraded, giving rise to large vesicles that displayed material immunoreactive with an antibody to beta-succinyl-coenzyme A synthetase, a hydrogenosomal enzyme. A protective role for polyamines as stabilizing agents in the trichomonad hydrogenosomal membrane is proposed.

Visceral leishmaniasis in the hoary zorro Dusicyon vetulus: a case of mistaken identity.

The historical identification of the Brazilian 'north-eastern' zorro as Dusicyon vetulus is questioned in relation to its incrimination as a reservoir of Leishmania chagasi, the agent of American visceral leishmaniasis. Comparative cranial and dental morphology showed that specimens of this north-eastern species more closely resemble the crab-eating zorro Cerdocyon thous, conforming with the documented geographical ranges of the respective species. We conclude that the single 'wild' canid host of L. chagasi in the neotropics in C. thous.

Morphogenesis of the hydrogenosome: an ultrastructural study.

The morphogenesis of hydrogenosomes in several trichomonad species (Tritrichomonas foetus, Trichomonas vaginalis, Tritrichomonas suis, Trichomonas gallinae, Tritrichomonas augusta and Monocercomonas sp) was investigated by transmission electron microscopy of thin sections and freeze-fracture replicas of whole cells or the isolated organelle. Close proximity, and even continuity, between endoplasmic reticulum and hydrogenosomes was observed. Structures were seen connecting hydrogenosomes to each other and to cytoplasmic structures. Morphological evidence is presented showing that in all the trichomonads here studied, hydrogenosomes, like mitochondria, may divide by two distinct processes: segmentation and partition. In the segmentation process, the hydrogenosome grows, becoming enlongated with the appearance of a constriction in the central portion. Microfibrillar structures appear to help the furrowing process, ending with a total fission of the organelle. In the partition process, the division begins by an invagination of the inner hydrogenosome membrane, forming a transversal septum, separating the organelle matrix into two compartments. We suggest that myelin-like structures seen either in close contact with or in the vicinity of the hydrogenosomes may be a source of membrane lipids for hydrogenosome growth.