The tampon test for trichomoniasis: a comparison between conventional methods and a polymerase chain reaction for Trichomonas vaginalis in women

OBJECTIVES: Trichomonas vaginalis is the most common STD worldwide and the infection has been linked with an increased risk of HIV transmission. We present a detailed comparison between conventional collection and testing methods and the polymerase chain reaction (PCR) tampon test for T vaginalis. METHODS: Women were tested for the presence of T vaginalis by PCR analysis of a tampon specimen and by conventional methods which included one or more of the following: culture and microscopy from a high vaginal swab (HVS) or endocervical swab (ECS), and microscopy of a Papanicolaou (Pap) smear. RESULTS: T vaginalis was detected in 51/590 (8.6%) conventional tests and 93/590 (15.8%) tampon specimens. Retesting of all tampon PCR positive specimens confirmed 89/93 (95.7%) tests. Using the tampon PCR as the reference, the sensitivities of the different conventional sampling and testing methods for the detection of T vaginalis were 8.3% (5/60) for ECS microscopy or culture, 31% (13/42) for HVS microscopy or culture, 52.8% (19/36) for HVS directly inoculated into Trichomonas medium and 59.4% (38/64) for Pap smear. CONCLUSIONS: No conventional test in the remote setting has comparable sensitivity to PCR. The Pap smear is the next most sensitive, but requires a speculum examination. The use of PCR will allow inclusion of T vaginalis into STD screening programmes in both developed (lower prevalence) and developing (higher prevalence) countries.


     

Thromboxane mediates the ischemia-induced neutrophil oxidative burst

Indirect evidence exists that the reperfusion of ischemic tissue activates white blood cells. Thus local and systemic reperfusion injuries are prevented by making animals leukopenic or by inhibiting white blood cell lung entrapment by blocking thromboxane A2 generation. This study tests directly whether ischemia and reperfusion activates neutrophils, as measured by their oxidative burst, and whether thromboxane mediates this event. Anesthetized rats underwent 4 hours of bilateral hind limb tourniquet ischemia followed by 60 minutes of reperfusion. Plasma thromboxane B2 levels increased to 2750 pg/ml at 5 minutes of reperfusion, higher than the sham control (n = 36) value of 370 pg/ml (p less than 0.01). In untreated ischemic animals (n = 30) the intracellular H2O2 production of circulating neutrophils, as assayed flow cytometrically by dichlorofluorescein oxidation, increased from a preischemic value of 133 to a peak of 251 femtomoles dichlorofluorescein/neutrophil at 5 minutes of reperfusion (p less than 0.01). Treatment of neutrophils with phorbol myristate acetate (PMA) 10(-7) mol/L led to a 91% increase in neutrophil H2O2 production before ischemia, and 5 minutes after reperfusion there was an enhanced response to PMA of 222% (p less than 0.01). Pretreatment of animals with the thromboxane-synthetase inhibitor OKY 046 (n = 36) prevented ischemia-induced thromboxane generation, neutrophil H2O2 production (p less than 0.05), as well as the enhanced response to PMA stimulation (p less than 0.05). Treatment with the thromboxane-receptor antagonist SQ 29,548 (n = 36) did not affect the increase in plasma thromboxane levels after ischemia but was as effective as OKY 046 in preventing the ischemia-induced increase in neutrophil H2O2 production and the enhanced response to PMA stimulation. These data indicate that lower-torso ischemia leads to neutrophil activation, manifest by H2O2 production, an event mediated by thromboxane.     

Leukotrienes but not complement mediate limb ischemia-induced lung injury.

Reperfusion after limb ischemia leads to sequestration of polymorphonuclear leukocytes (PMN) in the lungs and to leukocyte- (WBC) and thromboxane- (Tx) dependent respiratory dysfunction. This study examines the intermediary role of the chemoattractants leukotriene (LT)B4 and complement (C) fragments. Anesthetized sheep with chronic lung lymph fistulae underwent 2 hours of tourniquet ischemia of both hind limbs. In untreated controls (n = 7), 1 minute after tourniquet release, mean pulmonary artery pressure (MPAP) rose from 13 to 38 mmHg (p less than 0.05) and returned to baseline within 30 minutes. Pulmonary artery wedge pressure was unchanged from 3.6 mmHg. There were increases in plasma LTB4 levels from 2.46 to 9.34 ng/ml (p less than 0.01), plasma TxB2 levels from 211 to 735 pg/ml (p less than 0.05), and lung lymph TxB2 from 400 to 1005 pg/ml (p less than 0.05). C3 levels were 96% of baseline values. Thirty minutes after reperfusion, lung lymph flow (QL) increased from 4.3 to 8.3 ml/30 minutes (p less than 0.05), lymph/plasma protein ratio was unchanged from 0.6, and the lymph protein clearance increased from 2.6 to 4.6 ml/30 minutes (p less than 0.05), data consistent with increased microvascular permeability. WBC count fell within the first hour from 6853 to 3793/mm3 (p less than 0.01). Lung histology showed leukosequestration, 62 PMN/10 high-power fields (HPF) and proteinaceous exudates. In contrast to this untreated ischemic group, animals treated with the lypoxygenase inhibitor diethylcarbamazine (n = 5) demonstrated a blunted reperfusion-induced rise in MPAP to 17 mmHg (p less than 0.05). There were no increases in LTB4, TxB2, QL or lymph protein clearance (p less than 0.05). WBC count was unchanged and lung leukosequestration was reduced to 40 PMN/10 HPF (p less than 0.05). Decomplementation with cobra venom factor (n = 4) resulted in plasma C3 levels, 10% of baseline, but tourniquet release still led to pulmonary hypertension, elevated LTB4, TxB2 levels, and a decline in WBC count similar to that of untreated ischemic control animals. Histology showed 46 PMN/10 HPF sequestered in the lungs. Further, bilateral hind limb ischemia in either genetically sufficient (n = 10) or deficient (n = 10) C5 mice led to significant lung leukosequestration of 108 and 106 PMN/10 HPF, respectively, compared with 42 and 47 PMN/10 HPF in sham C5(+) and C5 (-) mice (n = 20) (p less than 0.01). These results suggest that the lung leukosequestration and increased microvascular permeability after lower torso ischemia are mediated by the chemotactic agent LTB4, but not by the complement system.     

Lower torso ischemia-induced lung injury is leukocyte dependent.

Lower torso ischemia leads on reperfusion to sequestration of polymorphonuclear leukocytes (PMN) in the lungs and increased permeability. This study tests the role of circulating leukocytes (WBC) in mediating this lung injury. Anesthetized sheep prepared with chronic lung lymph fistulae underwent 2 hours of bilateral hind limb tourniquet ischemia. In untreated controls (n = 7), 1 minute after reperfusion there were transient increases in mean pulmonary arterial pressure (MPAP) from 13 to 38 mmHg (p less than 0.05) and pulmonary microvascular pressure (Pmv) from 7 to 18 mmHg (p less than 0.05), changes temporally related to a rise in plasma thromboxane (Tx) B2 levels from 211 to 735 pg/ml (p less than 0.05). Lung lymph TxB2 levels rose from 400 to 1005 pg/ml at 30 minutes (p less than 0.05), and remained elevated longer than plasma levels. Lung lymph flow (QL) rose from 4.3 to 8.3 ml/30 minutes (p less than 0.05) after 30 minutes of reperfusion and remained elevated for 2 hours. The lymph/plasma (L/P) protein ratio was unchanged from 0.6, while the lymph protein clearance increased from 2.6 to 4.6 ml/30 minutes (p less than 0.05), suggesting increased microvascular permeability. WBC counts decreased within the first hour of reperfusion from 6853 to 3796/mm3 (p less than 0.05), and lung histology after 2 hours showed proteinaceous exudates and leukosequestration of 62 PMN/10 high-powered fields (HPF), higher than the 22 PMN/10 HPF (p less than 0.05) in sham animals (n = 3). Recruitment of the pulmonary vasculature by left atrial balloon inflation (n = 3) resulted in a rise in MPAP to 20 mmHg. After 3 hours of balloon inflation, QL stabilized at 9.8 ml/15 minutes, and a pressure-independent L/P protein ratio of 0.3 was achieved. During reperfusion, QL increased further to 11.2 ml/15 minutes, the L/P ratio rose to 0.56 and the calculated osmotic reflection coefficient decreased from 0.70 to 0.44, documenting an increase in lung microvascular permeability. In contrast to these untreated ischemic controls, sheep (n = 7) rendered leukopenic with hydroxyurea or nitrogen mustard and having a total WBC count of 760/mm3 and PMN count of 150/mm3 did not manifest reperfusion-induced increases in MPAP, Pmv, QL, lymph protein clearance, or lung lymph. TxB2 level (p less than 0.05). Plasma TxB2 levels rose slightly at 30 minutes from 199 to 288 pg/ml (p less than 0.05). Lung histology was normal. These data indicate that WBC mediate the ischemia-induced increase in pulmonary microvascular permeability.     

Expression of Progastrin-Derived Peptides and Somatostatin in Fundus and Antrum of Nonulcer Dyspepsia Subjects With and Without Helicobacter pylori Infection

The hypergastrinemia and hyperacidity associated with Helicobacter pylori infection has been explained by either a primary excess of gastrin or a lack of inhibitory influence by somatostatin (SOM). The objective of the present study was to compare the concentrations of fundic and antral SOM- and antral progastrin-derived peptides in nonulcer dyspepsia (NUD) subjects with and without H. pylori infection. Antral and fundic mucosal biopsies were extracted and assayed for SOM and gastrin amide, glycine–extended gastrin (gastrin gly), progastrin, and total gastrin. There was a significant sixfold reduction in antral SOM but no change in fundic SOM content in H. pylori-infected subjects compared to uninfected subjects. Antral gastrin amide concentrations were significantly higher in infected subjects. However, the concentrations of the nonamidated gastrin forms (progastrin and glycine-extended gastrin) were significantly lower in the infected subjects, indicating an increased conversion of the precursor forms of gastrin to amidated gastrin, the type known to stimulate gastric acidity. The present study demonstrates that the elevated gastrin concentrations associated with H. pylori infection may be due to a reduction in the paracrine inhibitory effect of SOM on antral gastrin release. In addition, the posttranslational processing of gastrin to the amidated forms is increased in infected subjects, explaining why the elevation in antral gastrin is confined to the amidated form.