Thrombocyte substitution in acute leukemia. Effect of histocompatibility on the clinical efficacy

Thrombocyte substitution is an essential prerequisite for intensive cytoreductive therapy in acute leukemia. Evaluating 228 thrombocyte transfusions in 17 patients shows that the clinical effectiveness of thrombocyte concentrates can be increased by making the coordination of HLA antigens of donor and receiver as good as possible. When measured in the corrected increment (CI) 24 hours after transfusion, the effectiveness of A3/B1 match preparations (CI = 7.0 +/- 1.6) is significantly higher than that of random preparations (CI = 3.0 +/- 0.5). With the presence of HLA antibodies an effective substitution (CI24 greater than or equal to 4.5) can only be achieved by A3/B1 match thrombocytes. This can only be realized by applying the fourfold thrombapheresis of single donors.     

The transepithelial potential difference in the gills of the fiddler crab,Uca tangeri: Influence of some inhibitors

Summary Euryhaline Crustacea living in dilute media, counterbalance the salt loss by active absorption of NaCl across the gill epithelium. To investigate the mechanisms involved in salt absorption, transeptithelial potential difference (PD_te) was measured in isolated, perfused gills of the fiddler crab,Uca tangeri. The influence of some specific inhibitors of epithelial ion transport on the PD_te was tested.With symmetrical conditions on both sides of the epithelium, the posterior gills ofUca tangeri showed a spontaneous PD_te of +5 to +10 mV, that is an active transport potential which was positive on the bath side as referred to the hemolymph side. This potential decreased considerably after application of KCN or 2,4-dinitrophenol (DNP) to the perfusion saline.Omission of K⁺ from the perfusion saline or addition of ouabain led to a reversible drop of the PD_te, suggesting that the absorption of Na⁺ and also of Cl^– is driven by the (Na⁺+K⁺)ATPase located in the basolateral membrane of the epithelial cells.Perfusion of the hemolymph space with saline containing diphenylamine-2-carboxylate (DPC) or the loop diuretic furosemide resulted in a decrease of the PD_te.After application of amiloride to the bath saline the PD_te increased. Half-maximum response to amiloride was reached at a concentration of about 10^–5 mol·l^–1. This suggests that one of the Na⁺ pathways across the apical membrane may consist of Na⁺ channels.Abbreviations PD _te transepithelial potential difference - DPC diphenylamine-2-carboxylate - R _ps resistance of perfusate shunt - R _te transepithelial resistance - R _in input resistance - DNP 2,4-dinitrophenol Parts of this study have been reported at the 1st Congress of Comparative Physiology and Biochemistry, Liège 1984, and at the Vth European Colloquium on Renal Physiology, Frankfurt, 1985     

A monozygotic twin pair with Rett syndrome

Summary A five-year-old, monozygotic, Turkish female twin pair with Rett syndrome is described. The twins are almost completely concordant in all clinical signs. This observation suggests a genetic cause of Rett syndrome.     

Na+/H+ exchange regulates intracellular pH in a cell clone derived from bovine pigmented ciliary epithelium

The regulation of intracellular pH (pHi) was monitored in a virus-transformed cell clone derived from bovine ciliary body exhibiting characteristics of pigmented ciliary epithelium. Data were obtained from confluent monolayers grown on plastic coverslips in nominally bicarbonate-free media using the pH-sensitive absorbance of 5- (and 6-) carboxy-4',5'-dimethylfluorescein. Under resting conditions, pHi averaged 6.98 +/- 0.01 (SEM; n = 57). When cells were acid loaded by briefly exposing them to Ringer containing NH4+ and then withdrawing the NH4+, pHi spontaneously regained its initial value. In the presence of 1 mM amiloride or in the absence of Na+, this process was blocked, indicating the involvement of an Na+/H+ exchanger in the regulation of pHi after an acid load. Removing Na+ during resting conditions decreased cytoplasmatic pH. This acidification could be slowed by amiloride, which is evidence for reversal of the Na+/H+ countertransport exchanging intracellular Na+ for extracellular protons. Application of 1 mM amiloride during steady state led to a slow acidification. Thus the Na+/H+ exchanger is operative during resting conditions extruding protons, derived from cellular metabolism, or from downhill leakage into the cell. Addition of Na+ to Na+ -depleted cells led to an alkalinization, which was sensitive to amiloride, with an IC50 of about 20 microM. This alkalinization was attributed to the Na+/H+ exchanger and exhibited saturation kinetics with increasing Na+ concentrations, with an apparent KM of 29.6 mM Na+. It is concluded that Na+/H+ exchange regulates pHi during steady state and after an acid load.     

Detection of Sap-Transmissible Viruses by ELISA in Tissue-Propagated Plants of Red Raspberry during in vitro Culture

Apple mosaic virus and raspberry bushy dwarf virus were detected by ELISA in plantlets of red raspberry still growing in vitro. The plantlets were derived from explants which were excised from plants infected by either of the viruses mentioned. Detection by ELISA of prune dwarf virus in 4-month-old in vitro cultures of sour cherry was reported earlier. Thus, application of ELISA to tissue cultured plants in vitro seems to be an appropriate method for early detection of virus-infected plant cultures.     

High intensity and blue light regulated expression of chimeric chalcone synthase genes in transgenic Arabidopsis thaliana plants

Summary To establish a genetic system for dissection of light-mediated signal transduction in plants, we analyzed the light wavelengths and promoter sequences responsible for the light-induced expression of the Arabidopsis thaliana chalcone synthase (CHS) promoter fused to the -glucuronidase (GUS) marker gene. Transgenic A. thaliana lines carrying 1975, 523, 186, and 17 by of the CHS promoter fused to the GUS gene were generated, and the expression of these chimeric genes was monitored in response to high intensity light in mature plants and to different wavelengths of light in seedlings. Fusion constructs containing 1975 and 523 by of CHS promoter sequence behaved identically to the endogenous CHS gene under all conditions. Expression of these constructs was induced specifically in response to high intensity white light and blue light. The response to blue light was seen in the presence of the P_fr form of phytochrome. Fusion constructs containing 186 by of promoter sequence showed reduced basal levels of expression and only weak stimulation by blue light but were induced significantly by high intensity white light. These analyses showed that the expression of the A. thaliana CHS gene is responsive to a specific blue light receptor and that sequences between — 523 and — 186 by are required for optimal basal and blue light-induced expression of this gene. The experiments lay the foundation for a simple genetic screen for light response mutants.     

Stearidonic acid (18:4ω3) in Primula florindae

Stearidonic acid (18:4ω3), which is reported to be of rare occurrence in the plant kingdom and which is of considerable dietary and pharmaceutical interest has been found in three closely related Primula species. It occurs, together with γ-linolenic acid (3–4% of the seed oil total fatty acids), in significant percentages in Primula florindae (11%), P. sikkimensis (14%) and P. alpicola (14%). 18:4(ω3 may also be of chemotaxonomic interest in the genus Primula, as high levels may be typical for section Sikkimensis. The only commercial plant source of stearidonic acid known so far is the seed oil of Ribes nigrum.     

Characterization of Na+/H+ exchange in a rabbit corneal epithelial cell line (SIRC)

Continuous intracellular pH (pHi) measurements were performed in SIRC rabbit corneal epithelial cells using the pH-sensitive absorbance of intracellularly trapped 5(and 6)-carboxy-4',5'-dimethylfluorescein. Steady-state pHi in nominally bicarbonate free Ringer's solution averaged 6.87 +/- 0.02 (mean +/- S.E., n = 53). After intracellular acidification induced by the NH4Cl-prepulse technique, there was a sodium-dependent pHi recovery towards the normal steady-state pHi. The initial pHi recovery rate was a saturable function of extracellular sodium concentration with an apparent Km for external sodium of about 25 mM and a Vmax of about 0.28 pH units/min. Virtually no pHi recovery was observed in the absence of extracellular sodium. Sodium removal during steady state acidified the cells by 0.36 +/- 0.05 pH units (mean +/- S.E., n = 13) within 5 min. There was a dose-dependent inhibition of pHi recovery after NH4Cl prepulse by amiloride with an IC50 of about 15 microM. Amiloride in a concentration of 1 mM almost completely abolished pHi recovery. Amiloride (1 mM) applied during steady state induced an intracellular acidification of 0.2 +/- 0.03 pH units (mean +/- S.E., n = 7) within 5 min. These findings suggest that a Na+/H+ exchange is present in SIRC rabbit corneal epithelial cells. Na+/H+ exchange seems to be the major process involved in pHi recovery in SIRC cells after an intracellular acid load. Na+/H+ exchange also plays a role in the maintenance of steady-state pHi.     

True absorption and endogenous fecal excretion of manganese in relation to its dietary supply in growing rats

A conventional balance study with 48 male weanling rats was conducted to determine true absorption and endogenous fecal excretion of manganese (Mn) in relation to dietary Mn supply, following the procedures of a previously adapted isotope dilution technique. After 10 d on a diet with 1.5 ppm Mn, eight animals each were assigned to diets containing 1.5, 4.5, 11.2, 35, 65, or 100 ppm Mn on a dry-matter basis. Three days later, each rat was given an intramuscular⁵⁴Mn injection and kept on treatment for a balance period of 16 d. Apparent Mn absorption assessed for the final 8 d, averaged 8.6 μg/d without significant treatment effects, although Mn intake ranged from 18.6 to 1200 μg/d, in direct relation to dietary Mn concentrations. Mean fecal excretion of endogenous Mn for the six treatments was 0.9, 2.7, 7.4, 11.0, 16.3, and 17.7 μg/d, respectively. These values delineate the rates to which true absorption exceeded apparent rates. True absorption, as percent of Mn intake, averaged 28.7, 15.9, 11.7, 6.1, 3.4, and 2.0, respectively, as compared with mean values of 23.9, 10.9, 6.2, 3.4, 1.2, and 0.5 for percent apparent absorption. It was concluded that both true absorption and endogenous fecal excretion markedly responded to Mn nutrition and that the reduction in the efficiency of true absorption was quantitatively the most significant homeostatic response for maintaining stable Mn concentrations in body tissues.