Differential localization of IL-2- and -15 receptor chains in membrane rafts of human T cells

We studied whether cytokine receptors (Rs) on T cells associate with lipid microdomains ("rafts"). Low-dose phytohemagglutinin (PHA)-stimulated human T cells were separated into cytoplasmic, membrane, and raft fractions by buoyant density centrifugation. Examination of these fractions for the presence of interleukin (IL)-2- and -15R chains and associated signaling molecules by Western blotting revealed marked, selective enrichment of the IL-2/15R beta-chain in rafts before IL-2 stimulation. After IL-2 stimulation, a substantial amount of the beta-chain was found in the membrane fraction. This partial translocation was also observed for the beta-chain-associated molecules JAK-1, p56(lck), and grb-2. Finally, raft disruption with methyl-beta-cyclodextrin (MBCD) attenuated IL-2-induced tyrosine phosphorylation events and selectively decreased the surface expression of the IL-2/15R beta-chain detected by flow cytometry. These results show that the IL-2/15R beta-chain is enriched in rafts obtained from low-dose, PHA-stimulated T cells, that IL-2 binding alters this enrichment, and that this enrichment may be functionally relevant as a possible mechanism to ensure cytokine selectivity and specificity.     

Red cell 2,3-DPG,ATP, and mean cell volume in highly trained athletes

Summary 20 male elite long distance runners were compared to a control group of blood donors to determine the effect of training on red blood cells. The acute effects of exercise on red cells were investigated in 11 of the runners following a race of 15–30 km. The runners had elevated resting values of red cell 2,3-DPG (P<0.05) and mean cell volume (P<0.01); blood Hb and ATP were not different from concentrations in the control group. The red cell status of the athletes may be explained by an increased proportion of young erythrocytes in runners. No statistically significant changes in red cell 2,3-DPG, ATP, mean cell volume or blood Hb were found post exercise.     

Preventive Measures in Mite Asthma

To evaluate the effect of preventive measures 46 patients, all allergic to house-dust mites (Dermatophagoides spp.), were randomly allocated to a study and a control group. According to the patients' subjective recordings of symptom score and use of medicine, compared with the control group, the study group had improved. There was, however, no improvement when comparing the objective recordings of morning and evening peak flow and use of medicine, and it is concluded that the preventive measures in this programme are not very effective for patients allergic to house-dust mites. The reduction in indoor humidity in the study group was limited and, as a high indoor humidity is the cause of huge populations of house-dust mites in homes, it is emphasized that future programmes of preventive measures should focus more on damp problems, particularly those related to bad housing construction.     

Synthesis of poly(vinyl ether)s with perfluoroalkyl pendant groups

2-Perfluoro(alkyl)ethyl vinyl ethers, F(CF₂)_nCH₂CH₂OCH?CH₂, (n = 6 or 8), were synthesized and polymerized by means of cationic initiators (HI/ZnI₂ and CF₃SO₃H/(CH₃)₂S). The perfluorohexyl-substituted poly(vinyl ether) is completely amorphous. The polymer with perfluorooctyl segments shows side chain crystallization with a disordering transition. For the corresponding perfluorooctyl monomer a liquid-crystalline phase was observed before melting. Copolymerization experiments of the flurocarbon-segmented monomers with a vinyl ether containing a cyanobiphenyl group in the side chain did not give homogeneous copolymers. This is attributed to the slower rate of polymerization of the fluorinated vinyl ethers as compared with the liquid-crystalline comonomer.     

Mechanics of porcine coronary arteries<Emphasis Type="Italic">ex vivo</Emphasis> employing impedance planimetry: A new intravascular technique

Our objective was to evaluate methodological aspects of impedance planimetry, a new balloon catheter-based technique, for the investigation of coronary artery mechanical wall properties. We used a four ring-electrode electrical impedance measuring system that was located inside a balloon. Two of the electrodes were used for excitation and connected to a generator producing a constant alternating current of 250 mA at 5 kHz. The other two electrodes for detection were placed midway between the excitation electrodes. The balloon was distended with electrically conducting fluid through an infusion channel. The vessel cross-sectional area (CSA) was measured according to the field gradient principle by measuring the impedance of the fluid inside the balloon. Impedance planimetry was applied in the three major branches of the coronary arteries of seven extracted porcine hearts to assess luminal CSAs in response to internal pressurization. The biomechanical wall properties were evaluated by computing the strain [(r?r ₀)·r ₀ ^?1, wherer is the vessels inner radius computed as (CSA · π^?1)^½ andr ₀ is the radius of the vessel at a minimal distension pressure], the tension [(r·dP), wheredP is the transmural pressure difference], and the pressure elastic modulus (ΔP·r·Δr ^?1). We found thatin vitro testing demonstrated that impedance planimetry was accurate and reproducible. The technique has controllable sources of crror. Measurements were performed with consecutively increasing pressures in the range 1–25 kPa (8–188 mmHg, 0.01–0.25 atm). The CSAs increased nonlinearly and were significantly larger in the left anterior descendent coronary artery (LAD) (1 kPa, mean 5.0 mm²; 25 kPa, mean 21.8 mm²) than in both the left circumflex (Cx) (4.5–16.0 mm²) and the right coronary artery (RCA) (2.8–15.6 mm²) (analysis of variance,P<0.001 for both). The circumferential wall tension-strain relation showed exponential behavior. For a given strain, tension values for LAD were significantly lower than those of Cx (P<0.01). The pressure elastic modulus-strain relation also was exponential, and values for Cx were significantly lower than values for LAD (P<0.001) and RCA (P<0.05). Impedance planimetry was applied to the study of coronary artery biomechanicsex vivo. The LAD had the largest CSA, and the Cx was the least compliant. Methodological aspects of anin vivo introduction of the method require additional evaluation.     

In vitro study on the impact of fish sera on the survival and fine structure of the eel-pathogenic acanthocephalanParatenuisentis ambiguus

The effects of fish sera on the growth and fine structure of infective larvae of the eel-pathogenic acanthocephalanParatenuisentis ambiguus (Eoacanthocephala: Tenuisentidae) were studied under in vitro conditions using sera from the final hostAnguilla anguilla and from two accidental fish hosts as well as fetal calf serum. As controls larvae were also kept in medium in the absence of serum and in experimentally infected eels. Sera from the accidental fish hosts carp and rainbow trout exerted toxic effects on the acanthocephalans. Worms maintained in medium containing sera from these two fish were contracted and displayed inverted probosces. Moreover, the tegument exhibited vacuolization and the formation of necrotic areas, including lysis of the mitochondria. Due to these effects, the parasites died at 21 (rainbow trout) or 21–50 days (carp) postincubation. Eel sera had no toxic effect on the infective larvae. The growth of the larvae in medium depended on the composition of the latter, but was reduced as compared with that in the natural final host. Based on these results, we conclude that components of the hosts' blood sera play a role in the determination of the host specificity ofP. ambiguus.