Viremia and excretion of TT virus in immunosuppressed heart transplant recipients and in immunocompetent individuals.

BACKGROUND: The TT virus (TTV) was discovered in patients with symptomatic posttransfusion hepatitis, but many viremic individuals are asymptomatic. Inadvertent transfusion-associated transmission must therefore be anticipated. We screened blood donors and heart transplant recipients for TTV infections. METHODS: Nested polymerase chain reaction was used to detect TTV DNA in plasma, serum, urine, and fecal samples from 600 blood donors, from 100 healthy individuals, and from 495 heart transplant recipients. RESULTS: A total of 3.2% of the blood donors, but 25% of the heart transplant recipients were viremic. TTV subtypes G1a/b and G2a/b were observed in both groups, but the subtype distributions were discrepant. A severe, acute infection with TTV subtype 3 was observed in one blood donor. The prevalence of TTV infections in heart transplant recipients was not correlated to transfusion frequency. Nine viremic heart transplant recipients and their 75 blood donors were studied in detail. Seven blood donors were viremic, but only two "pairs" of viremic blood donors and transfusion recipients had identical TTV isolates. TTV DNA was detected in the feces of 5% (5/100) of immunocompetent individuals (staff), in 46% (52/112) of viremic heart transplant recipients, and in the urine of 55% (20/36). TTV DNA was detected in six of six batches of pooled "virus-inactivated" plasma (solvent/detergent treated), and in none of eight batches of commercial immunoglobulins. CONCLUSION: Although TTV is transfusion-transmissible, the parenteral transmission rate may have been overestimated. Many TTV infections are apparently acquired by nonparenteral routes. Immunoglobulins are safe but pooled plasma is not safe regarding TTV transmission.

Comparison of the satiating effect of the CCKA receptor agonist A71378 with CCK-8S.

The satiating effect of the selective cholecystokininA (CCKA) receptor agonist A71378 and the mixed A and B receptor agonist CCK-8S were compared in 24-h food-deprived rats. After systemic application of 1.6, 8.0, and 40 micrograms/kg A71378 or CCK-8S, respectively, food intake was measured for 24 h. During the first hour A71378 and CCK-8S decreased food intake similarly. Two and 4 h after treatment, the satiating effect of A71378 continued. In contrast, 2 h after administration of CCK-8S a slight effect was observed at the highest dose (40 micrograms/kg), which totally disappeared after 4 h. In summary, the effect of A71378 on food intake is longer lasting compared to CCK-8S.

CCKB receptor signaling in rat pituitary GH3 cells. CCK-8S-induced intracellular calcium mobilization by Ca2+ release and Ca2+ influx.

We describe the effect of sulphated cholecystokinin octapeptide (CCK-8S) on [Ca2+]i in rat pituitary GH3 cells. Investigations were performed on fluo-3 loaded cells by using a confocal imaging system MRC-600 (Bio-Rad). Because CCK-8S mobilized intracellular calcium in cells bathed in Ca(2+)-free buffer it must be able to release calcium from internal stores. Furthermore, influx of Ca2+ from outside the cells seems to contribute to CCK-8S induced increases in [Ca2+]i as demonstrated by calcium mobilization in GH3 cells preincubated with thapsigargin in Ca2+ containing buffer.

Comparative 3H-CCK-8S binding studies on CCKB-type receptors in guinea-pig cortex and continuous cell lines.

The present study was undertaken to compare binding characteristics of CCKB-type receptors in guinea-pig cortex, Jurkat T-cells, GH3 cells and C6 cells. The rank order of potency of a variety of CCK agonists and antagonists in inhibiting specific [3H]CCK-8S binding was highly correlated for the 4 CCKB receptor models as demonstrated by a computer-assisted statistical analysis. Taking the ligand binding profiles as the criterion it is concluded that CCKB receptors in guinea-pig cortex, Jurkat T-cells, pituitary GH3 cells and rat glioma C6 cells share identical pharmacological properties.

Binding of cholecystokinin-8 (CCK-8) peptide derivatives to CCKA and CCKB receptors.

The structural requirements for the selective binding of cholecystokinin-8 (CCK-8)-related peptides to peripheral (CCKA) receptors are not sufficiently understood. In this study, the interaction of a series of newly shortened analogues of CCK-8 with both receptor subtypes was analyzed by displacement studies using [3H]-CCK-8 and 125I-Bolton-Hunter (BH)-CCK-8 as radioligands. The pentapeptide derivative of CCK-8, succinyl-Tyr (SO3H)-Met-Gly-Trp-Met-phenethylamide, was found to bind selectively with high affinity to the CCKA receptor. The replacement of Met28 and/or Met31 by norleucine and of L-Trp30 by its D-analogue had no significant effect on the binding properties of the peptide. Further C-terminal shortening resulted in a drastic loss of affinity and selectivity of the CCK receptor binding.

Type B cholecystokinin receptors on rat glioma C6 cells. Binding studies and measurement of intracellular calcium mobilization.

To our knowledge, no brain derived cell line has been shown as yet to bear cholecystokinin(CCK)B receptors. In this paper, CCK binding sites were identified on rat C6 glioma cells. Pharmacological characterization demonstrated a single class of high affinity binding sites (Kd = 1.7 +/- 0.3 x 10(-10) M) and a binding capacity of 6.1 +/- 1.8 fmol/mg protein. These CCK binding sites displayed a typical CCKB pharmacological profile as shown in competition studies by using several CCK-related compounds and nonpeptide CCK antagonists discriminating between CCKA and CCKB sites. In order to demonstrate that CCK binding sites constitute a functional receptor CCK-8S induced mobilization of free intracellular calcium was investigated in single C6 cells by using a laser scanning confocal imaging system. Since rise in [Ca2+]i noted by stimulation of C6 cells with CCK-8S could be blocked by the CCKB receptor antagonist L-365,260 (100 nM) but not by the CCKA receptor antagonist L-364,718 (100 nM), CCK induced calcium signal is triggered by activation of CCKB receptors in C6 cells. The rat C6 glioma cell line may serve as a useful model for studying CCKB receptor in brain.

[An improved synthesis of pentagastrin (Acignost)]. / Eine verbesserte Synthese von Pentagastrin (Acignost).

The large-scale synthesis of the pentapeptide Boc-beta-Ala Trp-Met-Asp-Phe-NH2 is described and a convenient procedure for purification of the crude peptide will be reported.