Elongation factor 2 as a target for selective inhibition of protein synthesis in vitro by the novel aromatic biasamidine

By the formation of cGMP the NO-sensitive guanylyl cyclase plays a key role within the NO/cGMP signaling cascade involved in vascular regulation and neurotransmission. The prosthetic heme group of the enzyme acts as the NO sensor, and binding of NO induces conformational changes leading to an up to 200-fold activation of the enzyme. The unexpected fast dissociation half-life of NO of a few seconds is fast enough to account for the deactivation of the enzyme in biological systems. YC-1 and its analogues acting as NO sensitizers uncovered a new pharmacologically and conceivably physiologically relevant regulatory principle of the enzyme.Two existing isoforms of the heterodimeric guanylyl cyclase (₁₁, ₂₁) are known that are functionally indistinguishable. Up to now, the NO-sensitive guanylyl cyclase has been considered as a soluble enzyme. However, recent evidence about the ₂₁ isoform interacting with a PDZ domain of the postsynaptic scaffold protein PSD-95 suggests that the ₂ subunit directs a membrane association of this isoform. The interaction with PSD-95 locates the ₂₁ isoform in close proximity to the NO-generating NO synthase thereby enabling the NO sensor to respond to locally raised NO concentrations.     

Localization of carboxypeptidase A-like enzyme in rat kidney

In this study we demonstrate that carboxypeptidase A (CPA)-like enzyme is expressed in rat kidney. The major metabolites of angiotensin (Ang) I by the rat renal mesangial cell extract at 37 degrees C, pH 7.4, were Ang 1-9 and Ang II. Quinaprilat did not influence the formation of Ang 1-9, but it inhibited formation of Ang II. The formation of Ang 1-9 was inhibited by potato carboxypeptidase inhibitor, 1,10-phenanthroline or EDTA. Lowering the pH from 7.4 to 4.0 also inhibited the formation of this nonapeptide. These findings suggest that a metallocarboxypeptidase is responsible for Ang 1-9 production. Using monoclonal antibodies to CPA, Western blot showed the presence of CPA-like enzyme in the extracts prepared from the mesangial cells or kidney cortex of the rat. Immunohistochemistry showed that CPA-like enzyme is localized in the mesangial glomerular cells and adventitia of kidney blood vessels, whereas it was absent in the renal tubules. Our data suggest that a CPA-like enzyme could be added to a repertoire of enzymes present in the rat mesangial cells and adventitia of renal blood vessels.     

Changes in serum copper level during detoxification of acutely poisoned drug addicts

Although it is known that drug addicts are a high-risk group for disruption of many homeostatic processes, little is know about changes in serum trace elements concentrations after taking the psychoactive substances. The aim of the study was to check the influence of the taking homemade heroin on serum level of copper. Blood samples were taken from 30 opiate addicts, and copper concentrations were measured by the means of atomic absorption spectrophotometry. The result of the study show that in the examined group, copper serum concentrations (1.35 mg/L) upon admission to the clinic were higher than in the control group (1.11 mg/L) but decreased during hospitalization (1.18 mg/L). There was no correlation between duration of stay at the hospital and changes in serum copper concentration.     

Phenol oxidising enzymes in the grain aphid’s saliva

Sucrose-agarose gels and sucrose liquid diets were used to study the phenol oxidising enzymes in the salivary secretions of the grain aphid, Sitobion avenae (Fabricius). Activity indicating the presence of two oxidoreductases, polyphenol oxidase (PPO) and peroxidase (Px), was found. Both enzymes were present in the aphids stylet sheath (gelling saliva) but only polyphenol oxidase activity was found in the halos around sheaths and thus in watery saliva. Electrical penetration graphs (EPG) revealed that the secretion of these enzymes into the gels, by an individual aphid, was associated with its probing activity observed during penetration of the epidermal and mesophyll tissues. The grain aphids PPO, secreted in its saliva reacted with a range of phenolic compounds. As most of these phenolics occur naturally in cereals, the grain aphid could modify its host-plants phenolic composition. The importance of the grain aphids polyphenol oxidase and peroxidase in detoxifying cereal phenolics is discussed.     

Seed Rain in Natural Grassland and Adjacent Ski Run in the Swiss Alps: A Preliminary Report

Seed rain was studied during one growing season in an intact high-alpine grassland and in a downhill ski run that had been machine-graded about 26 years earlier. The study plots were located at about 2500 meters above sea level. The number of trapped seeds per square meter in the grassland was significantly larger than in the ski run (930 versus 96, respectively). Alpha diversity in seed rain was about two times higher in the grassland than in the ski run. Seed rain was primarily influenced by site conditions but also varied in space and time, and both the actual number of diaspores and the species composition changed throughout the growing season. Most of the species found in the seed rain occurred in the standing vegetation, but some clearly arrived from outside. Seed rain in both sites was dominated by a few species, and no clear relationships were found between the species abundance in standing vegetation and in the seed rain. The results of this preliminary study contribute to a better understanding of plant behavior in high-alpine sites and will be helpful in planning and implementing restoration work above the timberline.     

17beta-estradiol regulation of human growth hormone (hGH), insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) axis in hypoestrogenic, hypergonadotropic women

OBJECTIVE: Ovarian hormonal function may be as important contributing factor to hGH-IGF-I-IGFBP-3 axis as age. AIM: To examine plasma hGH, IGF-1 and IGFBP-3 levels in women with premature ovarian failure compared to healthy normal controls and postmenopausal ones. PATIENTS: Group A-15 women with premature ovarian failure (POF) (mean: age 38.9+/-5.2 years, FSH 101.4+/-29.0 IU/l; 17beta-estradiol 22.5+/-14.6 ng/l). Group B consisted of 15 menopausal women (mean: age 54.7+/-2.7 years; FSH 81.9+/-32.1 IU/l; 17beta-estradiol 17.1+/- 8.0 ng/l). Group C - controls - 15 normally menstruating women (mean: age 37.1+/-9.0 years; FSH 6.2+/-1.0 IU/l; 17beta-estradiol 144.8+/-117.1 ng/l). METHODS: Body mass and BMI were measured. Basic fasting plasma hGH, IGF-I, IGFBP-3, insulin, testosterone and LH as well as prolactin (PRL), FSH and estradiol were assessed by RIA kits. Statistical analysis. Shapiro-Wilk test, Mann-Whitney u-test, Spearman rang correlation coefficient, stepwise multiple regression. RESULTS: Mean serum IGF-I level was the lowest (p<0.005) in group B (172.0+/-54.6 microg/l) and the highest in group C (273.6+/-109.0 microg/l). The mean plasma IGF-I level in group A was similar (NS) (208.3+/-66.5 microg/l) to that found in group B and lower (p<0.02) compared with that in group C. The lowest (p<0.005) serum IGFBP-3 level was found in group B (3.1+/-0.7 microg/l) compared to group C (4.4+/-0.3 microg/l). The mean plasma IGFBP-3 level (3.1+/-1.0 microg/l) in group A was lower than in group C (p<0.005) but identical as in group B. No statistically significant differences between groups were observed in mean hGH levels. Women in group A and C were younger (p<0.001) than those in group B. The lowest mean estradiol level was found in groups A and B. The highest was in group C (p<0.001). Mean plasma LH and FSH levels were higher (p<0.001) in groups A and B vs group C. In group C there were links between IGF-I and age (r=-0.60; p=0.014) The IGF-I/age relation disappeared in the groups A and B (rA=-0.26; rB=0.10; NS). The same regards IGFBP-3/ age link (rA=-0.44, NS; rB=0,31;NS). Estradiol level was related to hGH levels in group C (r=-0.54; p<0.05). In none of groups hGH/IGF-1 as well as IGFBP-3/hGH relations were found. Prolactin accounted for 69% of the variance in IGF-I level in the group B (p=0.003) and for 24% in group A (NS). Testosterone accounted for 88% (p=0.004) of the variance in IGF-I level in group B and IGFBP-3 was responsible for 86% (p=0.038) of the variance in IGF-I level in group C. Again IGFBP-3 was responsible for 47% (p=0.023) in group A and for 49% (p=0.04) in group B of the hGH variance. CONCLUSIONS: 17b-estradiol may be as important contributor to insulin-like growth factor-I (IGF-I) plasma level as age in hypoestrogenic, hypogonadotropic women.     

Somatostatin-like immunoreactivity in the amygdala of the pig

The distribution and morphology of neurons containing somatostatin (SOM) was investigated in the amygdala (CA) of the pig. The SOM-immunoreactive (SOM-IR) cell bodies and fibres were present in all subdivisions of the porcine CA, however, their number and density varied depending on the nucleus studied. The highest density of SOM-positive somata was observed in the layer III of the cortical nuclei, in the anterior (magnocellular) part of the basomedial nucleus and in the caudal (large-celled) part of the lateral nucleus. Moderate to high numbers of SOM-IR cells were also observed in the medial and basolateral nuclei. Many labeled neurons were also consistently observed in the lateral part of the central nucleus. In the remaining CA regions, the density of SOM-positive cell bodies varied from moderate to low. In any CA region studied SOM-IR neurons formed heterogeneous population consisting of small, rounded or slightly elongated cell bodies, with a few poorly branched smooth dendrites. In general, morphological features of these cells clearly resembled the non-pyramidal Golgi type II interneurons. The routine double-labeling studies with antisera directed against SOM and neuropeptide Y (NPY) demonstrated that a large number of SOM-IR cell bodies and fibers in all studied CA areas contained simultaneously NPY. In contrast, co-localization of SOM and cholecystokinin (CCK) or SOM and vasoactive intestinal polypeptide (VIP) was never seen in cell bodies and fibres in any of nuclei studied. In conclusion, SOM-IR neurons of the porcine amygdala form large and heterogeneous subpopulation of, most probably, interneurons that often contain additionally NPY. On the other hand, CCK- and/or VIP-IR neurons belonged to another, discrete subpopulations of porcine CA neurons.     

Late steps of egg cell differentiation are accelerated by pollination in Zea mays L.

 Egg cells were analysed cytologically during the female receptivity period in maize (Zea mays L., line A 188). Three classes of egg cell were distinguished: type A – small, non-vacuolated cells with a central nucleus; type B – larger cells with small vacuoles surrounding the perinuclear cytoplasm located in the middle of the cell; type C – big cells with a large apical vacuole and the mid-basal perinuclear cytoplasm. The less-dense cytoplasm of the vacuolated egg cells usually contained numerous cup- or bell-shaped mitochondria. The three egg types appear to correspond to three late stages of egg cell differentiation. The frequencies of each of the three egg types were monitored in developing maize ears before and after pollination. In young ears, with the silks just extending out of the husks, small A-type cells were found in about 86% of ovules. Their frequency decreased to about 58% at the optimum silk length, remained unchanged in non-pollinated ears, and fell to 16% at the end of the female receptivity period. However, after pollination and before fertilisation the frequency of these cells decreased to about 33%, and the larger vacuolated egg cells (types B and C) prevailed. At various stages of the receptivity period, pollination accelerated changes in the egg population, increasing the number of ovules bearing larger, vacuolated egg cells. Experiments with silk removal demonstrated that putative pollination signals act immediately after pollen deposition and are not species-specific. Received: 5 February 1999 / Accepted: 28 August 1999