Effect of Hydrochlorothiazide on Serum and Urinary Calcium and Urinary Citrate

Benzothiadiazines, potent oral diuretics, also inhibit carbonic anhydrase, although to a lesser degree than acetazolamide (Diamox). The latter has little effect on urinary calcium but causes hypocitriuria which predisposes to nephrolithiasis. The effect of benzothiadiazines on urinary calcium/citrate balance is less well known. In this study, the fall of urinary calcium and citrate was roughly 50% and 30%, respectively, in normal and hypertensive subjects during the prolonged administration of hydrochlorothiazide, a member of the benzothiadiazine family. Hence, in contradistinction to acetazolamide, this drug produces hypocalciuria but depresses the urinary citrate less. Consequently, the benzothiadiazines would not be expected to predispose to nephrolithiasis. In addition, hydrochlorothiazide was found to produce a 10-20% fall in creatinine clearance and an initial rise of roughly 0.7 mg./100 ml. in serum calcium concentration. There are indications that the benzothiadiazines affect the overall metabolism of calcium and citrate.     

The significance of relatedness and gene flow on population genetic structure in the subsocial spider Eresus cinnaberinus (Araneae: Eresidae)

Interdemic selection, inbreeding and highly structured populations have been invoked to explain the evolution of cooperative social behaviour in the otherwise solitary and cannibalistic spiders. The family Eresidae consists of species ranging from solitary and intermediate subsocial to species exhibiting fully cooperative social behaviour. In this study we, in a hierarchical analysis, investigated relatedness of putative family clusters, inbreeding and population genetic structure of the subsocial spider Eresus cinnaberinus. Five hierarchical levels of investigation ranging from large scale genetic structure (distances of 250 and 50 km level 1 and 2) over microgeographic structure (20 km² and 4 km², level 3 and 4) to a single hill transect of 200 m (level 5) were performed. The purpose of level 5 was two-fold: (1) to investigate the relatedness of putative family groups, and (2) to evaluate the influence of both family living and sampling design on higher level estimates. Relatedness estimates of putative family groups showed an average relatedness of R=0.26. There was no indication of inbreeding. In contrast to social spiders, genetic variation was abundant, H_e?0.10. The population genetic structure was intermediate between social and asocial spiders. Genetic variance increased continually across hierarchical levels. Family structured neighbourhoods biased differentiation estimates among level 5 samples (F_ST? 0.04) and level 3 and 4 samples (0.07ST<0.18), and apparent inbreeding among level 3 and 4 samples, F_IS>0, was caused by disjunct sampling from separate neighbourhoods. Larger scale samples were highly differentiated 0.12ST<0.26, depending on level and sampling design. Due to a distance effect family living did not influence estimates of the higher level 1. Although the dispersing sex among social spiders and the subsocial E. cinnebarinus differ, females versus males, female behaviour of both sociality classes lead to high genetic variance.     

Enzymes in cardenolide-accumulating shoot cultures of Digitalis purpurea L.

In contrast to undifferentiated cell suspension cultures of Digitalis lanata, photomixotrophic shoot cultures of Digitalis purpurea accumulate cardiac glycosides in substantial concentrations. They are used to investigate enzymes of the cardenolide pathway. All cardenolides are 5-configurated. The progesterone 5-reductase and the 3-hydroxysteroid-5-oxidoreductase are present in shoot cultures but not in undifferentiated cell cultures. These enzymes provide precursors for cardenolides, whereas the presence of the progesterone 5-reductase, also present in shoot cultures, is discussed with regard to its role in phytosterol biosynthesis and may be attributed to the general steroid pathway. The progesterone 5-reductase had an activity maximum during the early growth period seven days after onset of cultivation, whereas the corresponding progesterone 5-reductase activity was highest on day 11. The maximum cardenolide accumulation was after 24 days. The enzyme activities present in crude extracts from shoot cultures were characterized with regard to their requirements for NADPH and NADH, pH-optimum, temperature optimum, affinity to their substrates and their localization in the cell. The progesterone 5-reductase was purified 769-fold.Abbreviations DW dry weight - FW fresh weight - PVP polyvinylpyrrolidone     

Stimulation by 6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate and glucocorticoids of phosphoenolpyruvate carboxykinase in the isolated perfused rat liver (Short Communication)

Dibutyryl cyclic AMP stimulated the activity of phosphoenolpyruvate carboxykinase in perfused livers of rats, fed on a low-protein diet, linearly over a 6h period. The enzyme activity was also significantly elevated by dexamethasone, the effect being considerably lower than that of the cyclic nucleotide. Since the time-course of phosphoenolpyruvate carboxykinase activity in response to dibutyryl cyclic AMP resembled that observed after dibutyryl cyclic AMP injection into intact animals, it is suggested that induction of the enzyme in vivo is due to a direct action of the cyclic nucleotide on the liver. Combined administration of dibutyryl cyclic AMP and glucocorticoids did not lead to an additive increase of liver phosphoenolpyruvate carboxykinase activity, either in vivo or in the perfused organ.     

Cryopreservation of Digitalis lanata Ehrh. cell cultures: Preculture and freeze tolerance

Cryopreservation experiments were performed with Digitalis lanata cell cultures. The main stress was laid on the behaviour of the cells during the preculture period and the capacity of various preculture additives to induce freeze tolerance. The following compounds were used as preculture additives: trehalose, mannitol, sucrose, melibiose, proline, and sorbitol. They are listed in the order of their respective efficiency. Using trehalose, high post-thaw viability rates were achieved and the cells resumed growth after a short lag period. Melibiose was used as a preculture additive for the first time. Its suitability was in the range of that of sucrose. Proline and sorbitol were not able to induce freeze tolerance in Digitalis cells. Cell viability showed a considerable decrease at the beginning of the preculture period. This reduction was found to be transient in the presence of trehalose, mannitol, sucrose, and melibiose. The damaging effects of proline and sorbitol were too severe to be compensated for by the cells. The PAL activity increased markedly in the presence of proline, whereas the trehalose-treated and the control cells behaved nearly identical to one another.     

Spatial genetic patterns generated by two admixing genetic lineages: a simulation study

Two formerly geographically separated lineages of the zebra mussel Dreissena polymorpha had been given the opportunity to mix extensively across the newly built German Main–Danube canal. We had monitored this admixture of mussel lineages and had described spatial patterns in different genetic measures [Müller et al. 2001 (Heredity, 86: 103); 2002 (Proc. R. Soc. Lond., 269: 1139)]. Here, we present an individual-based model to assess the potential of spatial genetic patterns of detecting and quantifying admixture of mussel lineages. Genetic measures studied are (1) allele frequencies, (2) deviations from Hardy–Weinberg expectations of loci (deficit of heterozygotes, HWD) and (3) linkage disequilibria between unlinked loci (LD). For allele frequencies, we observed a cline over the zone of admixture in all simulations of mixing mussel lineages suggesting that these are appropriate for verification of their mixture. The point of the first contact between lineages was always detectable from their intermediate allele frequencies. LD and HWD were only spatially informative for diagnostic loci or loci with very strong differences in allele frequencies of lineages. For such loci, the probability of disequilibria was highest where lineages had met and decreased towards both sources of lineages Main and Danube. The overall probability of detecting any disequilibrium was higher for LD than for HWD and increased with an increasing rate of genetic interchange. Our simulation results are corroborated by our zebra mussel data and studies from literature. They are applicable to any case of two known linearly mixing genetic lineages.