Characterization of 14-3-3 proteins in adrenal chromaffin cells and demonstration of isoform-specific phospholipid binding

Isoform-specific antisera were used to examine which 14-3-3 isoforms were present in bovine adrenal chromaffin cells. The eta, tau and sigma isoforms were not detectable, and the epsilon isoform was present at only low levels. 14-3-3 isoforms were readily detected with antisera against the beta, gamma and zeta isoforms. The latter isoforms were found to leak from digitonin-permeabilized chromaffin cells, as expected for cytosolic proteins, but a proportion of each isoform was retained. In subcellular fractionation studies isoforms recognized by the beta and zeta antisera were found in the cytosol and Triton-insoluble cytoskeletal fractions, while the gamma isoform was found in cytosol and also in microsomal and chromaffin granule membrane fractions. The gamma 14-3-3 protein associated with granule membranes was partially removed by a high-salt/carbonate wash, and the membranes could bind further gamma from cytosol or from a purified brain 14-3-3 protein mixture. The binding of gamma 14-3-3 was not Ca(2+)-dependent, nor was it affected by phorbol ester, GTP analogues or cyclic AMP. Using pure phospholipid vesicles it was found that gamma and also epsilon 14-3-3 proteins bound directly to phospholipids. Little binding of brain beta, eta or zeta to phospholipid vesicles was detected. Brain 14-3-3 proteins were also able to aggregate phospholipid vesicles. Recombinant 14-3-3 isoforms (tau and the Xenopus protein) were able to stimulate Ca(2+)-dependent exocytosis in digitonin-permeabilized chromaffin cells. The Xenopus proteins lacks part of the extreme N-terminus, indicating that this domain is not essential for function in exocytosis.

[Age dependent changes in signal transduction of glucocorticoid hormones after physiological stress in liver cells of male Wistar rats]

After physiological stress older male Wistar rats showed a faster normalization of the corticosterone level in serum and of the concentration of unoccupied glucocorticoid receptors in liver cytosol than young ones, which is contrary to female rats. The nuclei binding of glucocorticoid receptor complexes (GRC) was significantly reduced in older control animals compared with young ones. The nuclei binding of GRC was reduced in young rats until 60 min after stress compared to controls, whereas it had been increasing in older animals at this time. Contrary to female rats, the addition of the endogenous ATP-stimulated translocation promoter (ASTP) alone or together with ATP did not elevate the nuclei binding, but it groups. Crossing experiments using nuclei of controls and GRC of control and stressed animals, resp., seem to disclose a longer association of GRC with the nuclei in old animals than in young ones.

Mechanism of inhibition of protein kinase C by 14-3-3 isoforms. 14-3-3 isoforms do not have phospholipase A2 activity

The ability of individual members of the 14-3-3 protein family to inhibit protein kinase C (PKC) has been studied by using a synthetic peptide based on the specific 80 kDa substrate for PKC (MARCKS protein) in two different assay systems. Recombinant 14-3-3 and isoforms renatured by a novel method after separation by reverse-phase h.p.l.c. were studied. The detailed effects of diacylglycerol and the phorbol ester phorbol 12-myristate 13-acetate on the inhibition were also investigated. This suggests that one of the sites of interaction of 14-3-3 may be the cysteine-rich (C1) domain in PKC. Since a region in secreted phospholipase A2 (PLA2) shares similarity with this domain, the ability of 14-3-3 to interact with mammalian PLA2 was studied. Cytosolic PLA2 has some similarity to the C2 region of PKC, and the effect of 14-3-3 on this class of PLA2 was also analysed. In contrast with a previous report, no PLA2 activity was found in brain 14-3-3, nor in any of the recombinant proteins tested. These include zeta 14-3-3 isoform, on which the original observation was made.

Relaxation from rigor of skinned trabeculae of the guinea pig induced by laser photolysis of caged ATP

The kinetics of ATP-induced rigor cross-bridge detachment were studied by initiating relaxation in chemically skinned trabeculae of the guinea pig heart using photolytic release of ATP in the absence of calcium ions (pCa > 8). The time course of the fall in tension exhibited either an initial plateau phase of variable duration with little change in tension or a rise in tension, followed by a decrease to relaxed levels. The in-phase component of tissue stiffness initially decreased. The rate then slowed near the end of the tension plateau, indicating transient cross-bridge rebinding, before falling to relaxed levels. Estimates of the apparent second-order rate constant for ATP-induced detachment of rigor cross-bridges based on the half-time for relaxation or on the half-time to the convergence of tension records to a common time course were similar at 3 x 10(3) M-1 s-1. Because the characteristics of the mechanical transients observed during relaxation from rigor were markedly similar to those reported from studies of rabbit psoas fibers in the presence of MgADP (Dantzig, J. A., M. G. Hibberd, D. R. Trentham, and Y. E. Goldman. 1991. Cross-bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres. J. Physiol. 432:639-680), direct measurements of MgADP using [3H]ATP in cardiac tissue in rigor were made. Results indicated that during rigor, nearly 18% of the cross-bridges in skinned trabeculae had [3H]MgADP bound. Incubation of the tissue during rigor with apyrase, an enzyme with both ADPase and ATPase activity, reduced the level of [3H]MgADP to that measured following a 2-min chase in a solution containing 5 mM unlabeled MgATP. Apyrase incubation also significantly reduced the tension and stiffness transients, so that both time courses became monotonic and could be fit with a simple model for cross-bridge detachment. The apparent second-order rate constant for ATP-induced rigor cross-bridge detachment measured in the apyrase treated tissue at 4 x 10(4) M-1 s-1 was faster than that measured in untreated tissue. Nevertheless, this rate was still over an order of magnitude slower than the analogous rate measured in previous studies of isolated cardiac actomyosin-S1. These results are consistent with the hypothesis that the presence of MgADP bound cross-bridges suppresses the inhibition normally imposed by the thin filament regulatory system in the absence of calcium ions and allows cross-bridge rebinding and force production during relaxation from rigor.

AgNOR- and PCNA-studies in astrocytomas of the optic nerve

Nine pilocytic astrocytomas of the optic nerve were investigated with the AgNOR method and by immunohistochemistry with anti-PCNA antibodies. Four patients were male, 5 female (mean age 16.5 years, range 1-55 years). Seven pilocytic astrocytomas were low-grade tumors (grade I, WHO [2]), one tumor contained giant cells and prominent nuclei (grade II), the remaining tumor was anaplastic (grade III). In each case, 5 randomly chosen areas were investigated by light microscopy using objective 40. The PCNA staining index was defined as number of positive tumor cell nuclei divided by the total amount of tumor cell nuclei in the microscopic field. Tumors showing only one immunopositive cell nucleus at low magnification were considered to have a staining index below 0.1%. The staining index of the 7 grade I tumors was below 0,1%, the grade II tumor showed a staining index of 1%, and the anaplastic astrocytoma (grade III) demonstrated a 2.5% staining index. Investigations with the AgNOR method confirmed the above results of a low growth fraction in grade I-III grade astrocytomas of the optic nerve. Though low growth fractions have been reported in anaplastic astrocytomas and glioblastomas of the cerebrum, the low staining index in the anaplastic pilocytic astrocytoma of our series is remarkable: Instead of histological parameters like cellular and nuclear polymorphism and cellular density, the growth fraction could be a better parameter for the clinical course, which has in fact been benign in this case of an anaplastic pilocytic astrocytoma of the optic nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of fixation and preparation on the AgNOR distribution in routinely processed breast cancer specimens

AgNOR staining is mostly performed on unstained sections from paraffin-embedded material. This well-established application may be limited, if only a small biopsy or cytologic material is available. In this study, we analyzed the influence of different routine preparation types from histology and cytology on AgNOR staining results. 15 cases of ductal breast carcinoma were investigated using five different preparations per case: frozen sections, sections from formalin-fixed and paraffin-embedded, previously frozen material, sections from routinely formalin-fixed and paraffin-embedded fresh material, alcohol-fixed and air-dried cytological smears. After application of a modified combined Feulgen-AgNOR staining technique, AgNOR quantification on 150 nuclei per specimen was performed by TV-image analysis. For each preparation type adequate AgNOR staining results were obtained. Although there were a number of statistically significant correlations, the median values for the mean nuclear area, the mean number of AgNORs per cell, the mean AgNOR area per cell and the mean AgNOR sum area per cell were quite different within the 5 preparation types. This means that results, obtained with one preparation type, may not be taken as standard for a different one.

Effects of two kinds of decaffeinated coffee on serum lipid profiles in healthy young adults

OBJECTIVE

To investigate the effects of two kinds of decaffeinated coffee on serum lipid profiles in healthy young adults.

DESIGN

Randomized controlled study with three study groups and a parallel design, consisting of two consecutive periods.

SETTING

Outpatient clinical research center in a university clinic.

SUBJECTS

119 healthy students (60 male, 59 female) who were selected after a screening. All completed the study. Blood samples of three subjects (1 male, 2 female) were excluded from evaluation due to later diagnosed genetic anomalies of lipid metabolism.

INTERVENTIONS

All subjects consumed 750-1000 ml of caffeinated filtered coffee per day for a 2 week wash-in period. During the 6 week test period one group continued drinking the caffeinated coffee, while the two other groups consumed different kinds of decaffeinated coffee.

RESULTS

Consumption of both types of decaffeinated coffee did not lead to any significant changes in serum total and LDL cholesterol, triglycerides and apolipoprotein B. Furthermore, there were no significant differences in the reactions between the three groups. The diet did not change during the study.

CONCLUSIONS

Switch from regular to decaffeinated coffee had no cholesterol-elevating effects, irrespective of the type of coffee.

[Importance of AgNOR analysis in malignant tumors]

For the assessment of proliferative activity of malignant tumors several methods can be used. The method having been used at first has been the determination of mitotic index, playing an important role as a part of various grading systems until now. Besides of DNA cytometry, flow cytometry, determination of bromodeoxyuridine labeling index (BrdUr-LI) and immunohistochemical analysis of proliferation-associated antigens (e.g. Ki-67, PCNA), for several years AgNOR analysis has been used as a new technique, giving reproducible, exact results of proliferative activity of malignant tumors. Valuable information about proliferative activity of cells can be gained already by counting the AgNOR number per nucleus. Moreover the use of digital image analysis provides information about size and distribution of AgNORs. Evidently these data are more important than AgNOR number. In the hands of experienced pathologists and under standardized conditions AgNOR staining and AgNOR quantification are a valuable completion of established methods.

In patients with BCR-ABL-positive ALL in CR peripheral blood contains less residual disease than bone marrow: implications for autologous BMT

Residual leukemic cells are detectable at frequencies as low as 1 in 10(6) normal cells in patients with Philadelphia chromosome/BCR-ABL-positive leukemias in complete remission (CR) using reverse-transcriptase polymerase chain reaction (RT-PCR) with specific nested primers. The level of minimal residual disease (MRD) in the bone marrow (BM) and the peripheral blood (PB) may favor one of the two as the source for an autologous graft. In order to quantify MRD with RT-PCR we analyzed patients ficolled cells after limiting logarithmic dilutions in normal ficolled buffy-coat cells. In six patients with BCR-ABL-pos ALL who were in CR by conventional criteria (5 in CR1 and 1 in CR2), we studied a total of nine paired BM and PB samples prior to scheduled ABMT. A positive RT-PCR signals was detectable in all samples up to dilutions ranging from 1:10(1) to 1:10(3) in PB, and at higher titers ranging from 1:10(3) to 1:10(5) in the BM. The BM titers exceeded the corresponding PB titers in all nine sample pairs by at least 1 log. The mean difference was 1.55 log (geometric mean, n = 9) and is statistically significant (p < 0.03). We conclude that residual leukemia in BCR-ABL-positive ALL preferentially locates in the BM compartment, and we assume that PB may yield autologous grafts with significantly less leukemic contamination.

Estimation of urinary aldosterone using thin-layer chromatography and fluorimetry

AIMS

To develop a fluorimetric method for the estimation of urinary aldosterone; to establish a normal range in 24 hour and overnight urine samples; and to investigate the use of overnight urines for detecting hyperaldosteronism.

METHODS

Essential steps include hydrolysis of the 18 conjugate to release aldosterone and its oxidation with Benedict's solution, followed by thin-layer chromatography on silica gel and development of fluorescence on the plate with sulphuric acid.

RESULTS

There was a linear correlation between the amount of aldosterone and the area under the peak on the chromatogram. The mean intra-assay and interassay coefficients of variation were 4.4% and 6.8%, respectively. The mean aldosterone excretion in 67 adults was 15.7 (SD 8.1) nmol/24 hours. The mean overnight excretion in 65 adults was 2.6 (1.4) nmol/8 hours. The method detected raised concentrations in patients with primary and secondary aldosteronism.

CONCLUSIONS

This technique provides an accurate means of assaying urinary aldosterone. Overnight estimations seem to be as effective as 24 hour assays for identifying patients with hyperaldosteronism.

Cumulative chemotherapy increases mafosfamide toxicity for normal progenitor cells in AML patients: rationale for cryopreserving adapted-dose purged marrow early in first complete remission

To evaluate whether conditions for adapted dose mafosfamide (mafo) purging vary with accumulating chemotherapy, we studied the sensitivity of bone marrow CFU-GM in a total of 30 patients at different stages of treatment. We determined the dose of 95% CFU-GM growth-inhibition by mafo (ID95) in 23 patients with acute myeloid leukemia (AML) and 7 patients with lymphoid malignancies in first or second complete remission (CR). Sixteen AML patients were studied in early first CR prior to intensive consolidation with high-dose cytarabine (HDAC) and had a median ID95 of 130 (range 90-190) micrograms mafo/ml; the median ID95 in 3 of 7 AML-CR1 and 4 of 7 AML-CR2 patients who previously had HDAC therapy was 75 (range 55-110) micrograms/ml whereas a control group of 7 patients with lymphoid malignancies in CR1 showed a median ID95 of 100 (range 80-160) micrograms/ml. In AML the difference between patients in CR1 prior to HDAC and patients in CR1 after HDAC late consolidation or in CR2 was highly significant (p = 0.0006). We conclude that accumulating chemotherapy pre-treatment, in particular HDAC intensive consolidation, increases mafo toxicity for non-leukemic bone marrow CFU-GM and conversely decreases the mafo concentration applicable for adjusted-dose purging to eliminate residual leukemic cells. Hence mafo purging appears to be more efficient when done in early CR1 compared with later stages of disease.

Antibodies against the major brain isoforms of 14-3-3 protein. An antibody specific for the N-acetylated amino-terminus of a protein

14-3-3 proteins are apparently ubiquitous eukaryotic proteins that comprise a large number of isoforms. They have been implicated in the regulation of a wide range of biological processes [reviewed in Aitken et al. (1992) Trends Biochem. Sci. 17, 498-501]. We have raised specific antibodies against each mammalian brain isoform of 14-3-3 employing peptides synthesised from the amino-terminal regions. The peptides were, like the proteins from mammalian brain, N-acetylated. The antiserum specific for the epsilon isoform did not recognise the recombinant form of this protein (lacking the N-acetyl co-translational modification) expressed in E. coli until it was chemically acetylated.

[Effect of cytoplasmic factors on cell nucleus binding of glucocorticoid receptor complexes in the rat liver of two age groups]

The nuclei binding of activated glucocorticoid receptor complexes (GRC) was significantly diminished in old, unstressed rats compared with young ones. In animals killed at different times after physiological stress there were no significant age-dependent differences in nuclei binding of GRC, which recurred in the cytoplasm after 60, 120 and 180 min, resp. Addition of Ca2+ and ATP, resp., to the incubation system increased the nuclei bound part of GRC, especially in young animals. ATP-stimulated translocation promoter (ASTP), isolated from rat liver cytosol, raised the nuclei binding of GRC in both age groups, whereby the increase was only significant in young animals. In cytosol of old rats ASTP were found in a lower concentration; moreover, the reaction between ASTP, GRC, and the template seems to be impaired.

An N-terminal peptide from link protein is rapidly degraded by chondrocytes, monocytes and B cells

A peptide cleaved from the link-protein component of human and pig proteoglycan aggregates by trypsin and stromelysin was taken up and degraded further by human monocytes, B cells, chondrocytes and by mouse peritoneal macrophages. Monocytes were able to process the peptide twice as rapidly as peritoneal macrophages and some 16 times more rapidly than articular chondrocytes. The B cell line Priess, which unlike the monocytes and macrophages could not take up or degrade whole proteoglycan aggregates, was able to degrade the peptide at a rapid rate. Synthetic, unglycosylated peptides consisting of the first 16 and 13 N-terminal amino acids of human link protein, corresponding to its stromelysin-cleavage and trypsin-cleavage products, were also taken up and degraded in a similar manner to the natural products and, in addition, were able to block uptake of the 125I-labelled natural peptides. The isoelectric points of the re-secreted breakdown fragment from both the synthetic and natural peptides were identical and each peptide was processed by the cells to produce a single radiolabelled fragment. Each of these fragments was eluted with the same retention time during HPLC, indicating that the natural peptides were derived from the N-terminal region of the link. Since a proportion of the link protein extracted from human and pig cartilage has already undergone proteolysis to remove peptides from its N-terminal region, these peptides may be produced in articular cartilage during the normal process of turnover and ageing. Although a physiological function for this protein has not been established, it may have a homeostatic role in the regulation of proteoglycan synthesis.