Metabolic effect of telmisartan and losartan in hypertensive patients with metabolic syndrome

Background

Metabolic syndrome is a cluster of common cardiovascular risk factors that includes hypertension and insulin resistance. Hypertension and diabetes mellitus are frequent comorbidities and, like metabolic syndrome, increase the risk of cardiovascular events. Telmisartan, an antihypertensive agent with evidence of partial peroxisome proliferator-activated receptor activity-gamma (PPARγ) activity, may improve insulin sensitivity and lipid profile in patients with metabolic syndrome.

Methods

In a double-blind, parallel-group, randomized study, patients with World Health Organization criteria for metabolic syndrome received once-daily doses of telmisartan (80 mg, n = 20) or losartan (50 mg, n = 20) for 3 months. At baseline and end of treatment, fasting and postprandial plasma glucose, insulin sensitivity, glycosylated haemoglobin (HBA_1c) and 24-hour mean systolic and diastolic blood pressures were determined.

Results

Telmisartan, but not losartan, significantly (p < 0.05) reduced free plasma glucose, free plasma insulin, homeostasis model assessment of insulin resistance and HbA_ic. Following treatment, plasma glucose and insulin were reduced during the oral glucose tolerance test by telmisartan, but not by losartan. Telmisartan also significantly reduced 24-hour mean systolic blood pressure (p < 0.05) and diastolic blood pressure (p < 0.05) compared with losartan.

Conclusion

As well as providing superior 24-hour blood pressure control, telmisartan, unlike losartan, displayed insulin-sensitizing activity, which may be explained by its partial PPARγ activity.     

Genetic dissection of Al tolerance QTLs in the maize genome by high density SNP scan

Background

Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.

Results

Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al³⁺ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.

Conclusions

High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users.     

Blütenökologische Untersuchungen mit Hummeln VII. Die Anlockung von „Neulingen” Durch Blüten

Ohne ZusammenfassungMit 5 Textabbildungen (7 Einzelbildern).     

Blütenökologische Untersuchungen mit Hummeln. III. Das Verhalten der Tiere zu Duftstoffen,Duft und Farbe

Ohne ZusammenfassungMit 2 Textabbildungen.     

Blütenökologische Untersuchungen mit Hummeln

Ohne ZusammenfassungMit 12 Textabbildungen.     

The larval development of the telotrophic meroistic ovary in the bug Dysdercus intermedius (Heteroptera, Pyrrhocoridae)

Bug ovaries are of the telotrophic meroistic type. Nurse cells are restricted to the anterior tropharium and are in syncytial connection with the oocytes via the acellular trophic core region into which cytoplasmic projections of oocytes and nurse cells open. The origin of intercellular connections in bug ovaries is not well understood. In order to elucidate the cellular processes underlying the emergence of the syncytium, we analysed the development of the ovary of Dysdercus intermedius throughout the five larval instars. Up to the third instar, the germ cell population of an ovariole anlage forms a single, tight rosette. In the center of the rosette, phosphotyrosine containing proteins and f-actin accumulate. This center is filled with fusomal cytoplasm and closely interdigitating cell membranes known as the membrane labyrinth. With the molt to the fourth instar germ cells enhance their mitotic activity considerably. As a rule, germ cells divide asynchronously. Simultaneously, the membrane labyrinth expands and establishes a central column within the growing tropharium. In the fifth instar the membrane labyrinth retracts to an apical position, where it is maintained even in ovarioles of adult females. The former membrane labyrinth in middle and posterior regions of the tropharium is replaced by the central core to which nurse cells and oocytes are syncytially connected. Germ cells in the most anterior part of the tropharium, i.e. those in close proximity to the membrane labyrinth remain proliferative. The posterior-most germ cells enter meiosis and become oocytes. The majority of the ovarioles' germ cells, located in between these two populations, endopolyploidize and function as nurse cells. We conclude that the extensive multiplication of germ cells and their syncytial assembly during larval development is achieved by incomplete cytokineses followed by massive membrane production. Membranes are degraded as soon as the trophic core develops. For comparative reasons, we also undertook a cursory examination of early germ cell development in Dysdercus intermedius males. All results were compatible with the known basic patterns of early insect spermatogenesis. Germ cells run through mitotic and meiotic divisions in synchronous clusters emerging from incomplete cytokineses. During the division phase, the germ cells of an individual cluster are connected by a polyfusome rich in f-actin.     

Lung respiration, somatic activity and gas metabolism in embryonic chicks prevented from hatching by thiourea

Treating chick embryos with high doses of thiourea (32.8 mumol) on day 17 of incubation resulted in prevention of hatching and of active breathing. Furthermore, thiourea also prevented the increase of O2 consumption and the marked increase of somatic activity associated with the final hatching act. These findings provide evidence for the importance of active breathing in the prenatal period to initiate pipping and hatching of the avian embryo.     

Maleate effects on kidney peptidases and proteinuria of male and female rats. Histochemical and biochemical studies

The effects of maleate on membrane-bound and lysosomal peptidases were studied histochemically in the kidney and biochemically in the kidney and the urine of male and female rats 6 h after the administration of two different doses of sodium maleate (150 and 300 mg/kg body weight). Additionally, the proteinuria of experimental animals was electrophoretically analysed to detect maleate-induced alterations in the urinary protein composition. The histochemistry of the brush-border peptidases (aminopeptidase A, gamma-glutamyltransferase) showed dose-dependent maleate effects in the late pars convoluta and the pars recta of the proximal tubule (blurring of the brush-border enzyme reaction pattern). The female animals were more severely affected by both maleate doses. After maleate treatment, enzyme-activity measurements in the kidney homogenate supernatant and urine indicated dose-dependent structural destruction of the proximal tubule, especially of brush-border membranes, and revealed an increase in enzyme excretion. Both the maleate-induced enzyme excretion and proteinuria were more pronouncedly increased in females than in males. Electrophoretic analysis of urinary proteins revealed alterations in the urinary-protein composition after maleate treatment, which favoured the excretion of proteins with a molecular weight higher than 20,000 daltons. Again, sex-related differences in the maleate effects were demonstrated. The results indicate that maleate causes alterations in the brush-border membranes and, especially at higher doses, results in cellular destruction selectively in the late proximal tubule of rat kidneys. Selectivity was also encountered in the maleate effects on urinary-protein composition, suggesting that the tubular alterations lead to an inhibition of the reabsorption of mainly high-molecular-weight proteins. Although the nature of the effects was independent of sex, it appears that females are less well protected against tubular damage caused by maleate.