Modulation of the T cell compartment by blood transfusion. Effect on cytotoxic and helper T lymphocyte precursor frequencies and T cell receptor Vbeta usage

Recent data suggest that the favorable effect of pretransplant blood transfusion (BT) on transplant outcome depends on the HLA match. HLA-DR or haplotype shared transfusions lead to transplantation tolerance, and HLA-mismatched BT leads to immunization. The immunological mechanism involved is still unknown. To investigate the effect of HLA compatibility between blood donor and recipient on the T cell compartment, we determined the frequency of cytotoxic and helper T cell precursors specific for blood donor cells (n=20) and the T cell receptor Vbeta (TCRBV) repertoire of the CD4- and CD8-positive peripheral blood mononuclear cells before, at 2 weeks after, and at more than 10 weeks after BT (n=10). Patients had received one transfusion of a nonstored (<24 hr after withdrawal) erythrocyte concentrate without buffy coat containing on average 6x10(8) leukocytes. Eight patients shared an HLA-B and -DR antigen, nine patients shared one HLA-DR antigen, and three patients shared no HLA class II antigens with the blood donor. All patients showed a significant increase in both cytotoxic and helper T cell precursor frequencies against the blood donor 2 weeks after BT. In most patients, the frequencies reached pretransfusion levels again long after BT. In 5 of 10 patients, an expansion of one or more TCRBV families was observed in either the CD4 or CD8 compartment. This study demonstrates that BT, irrespective of the degree of HLA matching, induces activation of the T cell compartment. The degree of sharing of HLA antigens was not correlated with quantitative changes in cytotoxic T lymphocyte precursor or helper T lymphocyte precursor frequencies, or changes induced in the TCRBV repertoire. Cytotoxic and helper T lymphocyte precursor frequencies and TCRBV repertoire determined after BT do not give an indication for a state of tolerance prior to transplantation.     

Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats

We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mechanisms involved in this phenomenon. Male Wistar rats (N = 97, 200-300 g) were surgically manipulated to create four gut circuits: GD, gastric, pyloric and duodenal. These circuits were perfused under barostatically controlled pressure (4 cmH2O). Steady-state changes in flow were taken to reflect modifications in circuit resistances during three periods of time: normovolemic control (20 min), expansion (10-15 min), and expanded (30 min). Perfusion flow rates did not change in normovolemic control animals over a period of 60 min. BV expansion (Ringer bicarbonate, 1 ml/min up to 5% body weight) significantly (P < 0.05) reduced perfusion flow in the GD (10.3 +/- 0.5 to 7.6 +/- 0.6 ml/min), pyloric (9.0 +/- 0.6 to 5.6 +/- 1.2 ml/min) and duodenal (10.8 +/- 0.4 to 9.0 +/- 0.6 ml/min) circuits, but not in the gastric circuit (11.9 +/- 0.4 to 10.4 +/- 0.6 ml/min). Prazosin (1 mg/kg) and yohimbine (3 mg/kg) prevented the expansion effect on the duodenal but not on the pyloric circuit. Bilateral cervical vagotomy prevented the expansion effect on the pylorus during the expansion but not during the expanded period and had no effect on the duodenum. Atropine (0.5 mg/kg), hexamethonium (10 mg/kg) and propranolol (2 mg/kg) were ineffective on both circuits. These results indicate that 1) BV expansion increases the GD resistance to liquid flow, 2) pylorus and duodenum are important sites of resistance, and, 3) yohimbine and prazosin prevented the increase in duodenal resistance and vagotomy prevented it partially in the pylorus.     

Effect of cage size on ultradian locomotor rhythms of laboratory mice

The effect of cage size on spontaneous locomotor rhythms of laboratory mice was studied under simulated light-dark (12:12) cycles. On-line image analysis of bodily displacement yielded a locomotor signal over a period of 3 days. Continuous wavelet transform was applied to the signal, and ensemble averaging of eight mice revealed in the time-frequency plot bouts of increased motor activities. Notably, there were two bouts in the dark corresponding to ultradians of periods below 5 h: a first bout at the dark onset (at 0.6-1.0 cycle/h), and a second bout during the second half of the dark period (at 0.4-0.7 cycle/h). These increases of activity were more intense and distinct when the animals were kept inside the larger cage. Furthermore, the first bout disappeared when the animals were kept in the small cage for 3 days.     

Analysis of the components of Lycopus europaeus L. in body fluids during metabolism studies. Comparison of capillary electrophoresis and high-performance liquid chromatography

During pharmacokinetic studies with extracts obtained from medicinally used plants, analysis in body fluids is mainly performed by HPLC, an established separation method. In this paper high-performance capillary electrophoresis (HPCE) is investigated for its ability to separate such complex extracts. Crude extracts of Lycopus europaeus L. (Lamiaceae) are traditionally used against mild forms of hyperthyroidism. The metabolism of a 70% ethanolic extract with respect to some of its individual main components (rosmarinic and caffeic acid, luteolin-7-glucoside) and a mixture of the pure compounds were investigated using isolated perfused rat liver. After solid-phase extraction metabolites were determined using HPCE and HPLC separation techniques. A buffer solution composed of 0.05 mol l-1 Na2HPO4 at pH 7.0 with 30% acetonitrile was found to be the most suitable electrolyte for HPCE separation. The best mobile phase for isocratic HPLC was 0.03% TFA-acetonitrile (82:18, v/v). Data obtained with HPCE are in good accordance with those from HPLC; HPCE, however, is clearly more rapid and simple to perform.     

Comparison of real-time cholecystosonography and oral cholecystography

To evaluate the efficacy of real-time ultrasonography in detecting cholelithiasis, a series of outpatients and inpatients was examined by oral cholecystography and real-time cholecystosonography. In 163 patients, real-time cholecystosonography achieved a sensitivity of 0.91 and a specificity of 0.99. These values are equal to or better than those usually obtained in current B-mode cholecystosonography or some reported series of oral cholecystography. However, technically excellent and meticulously performed oral cholecystography achieves slightly better sensitivity and specificity than real-time cholecystosonography. The latter is suggested as the initial examination for hospitalized patients, those with abnormal liver function studies or gastric outlet obstruction, and pregnant women. Real-time ultrasonography should also be used when the gallbladder is not adequately opacified on initial oral cholecystography if a sequential dose examination cannot be readily accomplished.     

A microbiologic and ultrastructural investigation of germ-tube formation by oral strains of Candida tropicalis

Presumptive germ tube-positive and -negative Candida tropicalis strains have been obtained from both normal children and patients who have candidiasis. Examination of these strains by conventional microbiologic tests confirmed them to be C. tropicalis. Ultrastructural examination of the filaments produced by the positive strains revealed two types: true germ tubes and those with basally constricted cytoplasm. A fluctuation analysis of the positive strains showed two subgroups: germ tube-positive and -negative. It is suggested that C. tropicalis strains may be divided into germ tube-positive and -negative strains, and that germ-tube formation must therefore not be used as a sole criterion for identification of C. albicans.     

Feeding induced by pharmacological blockade of fatty acid metabolism is selectively attenuated by hindbrain injections of the galanin receptor antagonist, M40

Distal transcutaneous oxygen pressure measurement (TcPo2) is a noninvasive method of evaluating tissular hypoxemia in peripheral arterial disease. The poststress area of hypoxemia is a usefull technique for globally quantifying different parameters represented by TcPo2 curves during exercise. Although its use is increasingly widespread, the reproducibility of this method is poorly documented. TcPo2 was monitored three times at twenty-four hour intervals in 5 patients with stage II obliterative arterial disease during a treadmill walking test. In order to get uniform measurement conditions, each patient remained lying and then stood until TcPo2 became stable. The stress duration was calculated so that the pain step could not be reached. TcPo2 curves were digitized and a specific image analyzer was used to make replicate measurements. The area under the curve was computed, the horizontal axis determining the mean TcPo2 value at rest, the vertical axis representing the end of the exercise period. The corresponding areas under the curves ranged from 34 to 2212 mm2 (573.60; SD 826). Significant correlation coefficients were obtained among replicate measurements (first-second day, first-third day). However, owing to the wide range of area values, the authors decided to compute and use the coefficient of variation (STD/mean), since it was more representative of reproducibility. The mean of its value for 5 patients was 21%. Observation of the examination conditions resulted in several findings, especially the ability of certain patients to adapt their efforts to the exercise. These results indicate that TcPo2 poststress area measurements are reproducible, but the conditions of the exercise have to be rigorously defined and may still be improved.