Effect of somatostatin on kidney function and vasoactive hormone systems in health subjects

The acute effects of i.v. somatostatin (250 mcg bolus followed by 250 mcg/h continuous infusion for two hours) on renal hemodynamics, renal electrolyte and water handling, and urinary excretion of catecholamines and prostaglandins, as well as on plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, dopamine, glucagon, and plasma renin activity were studied in seven normal subjects. Somatostatin decreased effective renal plasma flow and glomerular filtration rate, osmotic and free water clearances, urine volume, and sodium and potassium excretion, while urinary osmolality, fractional excretion of sodium, and phosphate excretion increased significantly. Plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, and dopamine remained unchanged, while plasma renin activity (3.0 +/- 0.25 vs 2.4 +/- 0.2 ng AngI/ml/h; p less than 0.01) and glucagon levels (40 +/- 11 vs 20 +/- 16 pg/ml; p less than 0.01) decreased. Urinary excretion of norepinephrine, epinephrine, dopamine, PGE2, and PGF2 alpha was suppressed under somatostatin. A significant positive correlation was found between urinary dopamine and sodium excretion (r = 0.7; p less than 0.001) and urinary prostaglandin E2 and glomerular filtration (r = 0.52; p less than 0.01). Without accompanying changes in plasma osmolality and vasopressin concentration significant antidiuresis occurred, suggesting a direct tubular effect of somatostatin. However, the hormone-induced changes are due mainly to the decrease in renal plasma flow. The results demonstrate that somatostatin at supraphysiological doses exerts significant effects on the kidney.

Changes in plasma and urinary amino acid levels during diabetic ketoacidosis in children

Plasma and urinary concentrations of different amino acids were investigated during diabetic ketoacidosis (DKA) and 12, 24, 72 hours after initiation of therapy. In DKA, plasma concentration of glutamic acid, aspartic acid, valine, leucine and isoleucine significantly increased while that of asparagine and glutamine decreased compared to levels in well-controlled diabetic patients. The urinary excretion of branched-chain amino acids, histidine, serine and threonine was elevated while those of glutamic acid, glutamine, glycine and taurine were reduced. Among the different amino acids, histidine excretion had the highest variability. A strong correlation was found between the urinary excretion of several amino acids and that of the beta-2-microglobulin characterizing tubular dysfunction. Changes in the excretion of different amino acids reflect the altered metabolic state and renal function due to DKA.

A novel seed protein gene from Vicia faba is developmentally regulated in transgenic tobacco and Arabidopsis plants

We have isolated a novel gene, denoted USP, from Vicia faba var. minor, which corresponds to the most abundant mRNA present in cotyledons during early seed development; however, the corresponding protein does not accumulate in cotyledons. The characterized USP gene with its two introns is 1 of about 15 members of a gene family. A fragment comprising 637 bp of 5' flanking sequence and the total 5' untranslated region was shown to be sufficient to drive the mainly seed-specific expression of two reporter genes, coding for neomycin phosphotransferase II and beta-glucuronidase, in transgenic Arabidopsis thaliana and Nicotiana tabacum plants. We showed that the USP promoter becomes active in transgenic tobacco seeds in both the embryo and the endosperm, whereas its activity in Arabidopsis is detectable only in the embryo. Moreover, we demonstrated a transient activity pattern of the USP promoter in root tips of both transgenic host species.

Upstream sequences regulating legumin gene expression in heterologous transgenic plants

We have previously isolated a legumin gene LeB4 from Vicia faba and shown that a 4.7 kb DNA fragment containing the gene leads to seed-specific expression in transgenic tobacco plants. Here we report that the 2.4 kb upstream sequence alone, when fused to either the neomycin phosphotransferase II (nptII) gene or the beta-glucuronidase (uidA) gene, leads to high enzyme levels in transgenic seeds of both tobacco and Arabidopsis. beta-Glucuronidase (GUS) activity is especially intense in the cotyledons fading out towards the embryonal root tip, a result confirmed by in situ hybridization. Staining of endosperm cells is consistent in both species. Analysis of a series of promoter deletion mutants fused to the nptII gene and introduced into tobacco plants revealed that about 1 kb of 5'-flanking sequence is sufficient for high-level expression but indirect evidence suggests the presence of weak positive regulatory elements further upstream. Deletions leaving only 0.2 kb of upstream sequence reduce enzyme levels to less than 10%. A deletion which destroys the legumin box with its seed protein gene-specific CATGCATG motif has no obvious effects on expression levels.

The effect of long-term administration of lorglumide (CR 1409) on rat pancreatic growth and enzyme composition

The effects of lorglumide (CR 1409), a potent cholecystokinin (CCK) receptor blocker developed recently by the Rotta Research Laboratories, were studied on pancreatic growth and enzyme composition. In secretory studies, the inhibitory effect of 4 mg/kg of lorglumide administered subcutaneously proved to last more than 3 h. The trophic effect of exogenous CCK (600 ng/kg given three times daily for 2 weeks) was significantly decreased by the simultaneous administration of 4 mg/kg of lorglumide. To study the role of endogenous CCK released by feeding while maintaining pancreatic trophism, 4 mg/kg of lorglumide was administered subcutaneously four times daily during the feeding period for 2 weeks. Lorglumide significantly decreased pancreatic weight, pancreatic content of soluble protein, trypsinogen, and chymotrypsinogen, while decreases in DNA, lipase, and amylase failed to reach statistical significance. According to our experiments, high-doses of lorglumide could inhibit not only the trophic effect of exogenous CCK but also the effect of endogenous CCK released by food and lorglumide itself.

Oligopeptides interfering with calcium channels inhibit prolactin and growth hormone release by cultured anterior pituitary cells of the rat

A number of oligopeptides, protected at their N termini and possessing an aldehyde residue at their C terminal amino acids, are able to inhibit 45Ca2+ influx into anterior pituitary cells grown in monolayer culture and depolarized with high extracellular potassium concentration. In addition, the same oligopeptides interfere with hormone release, especially with that produced by lactotrophs. Our findings imply that oligopeptides may represent a new class of calcium channel ligands, and the pituitary cells are sensitive targets for them.

[Follow-up of blood and urinary amino acid concentrations in diabetic ketoacidosis in children]

Plasma and urinary concentrations of amino acids were investigated during diabetic ketoacidosis (DKA) and 12, 24, 72 hours after initiation of therapy. In DKA plasma concentration of glutamic acid, asparaginic acid, valine, leucine and isoleucine significantly increased while that of asparagine and glutamine decreased compared to levels in well controlled diabetic patients. Despite the elevated urinary excretion of branched chain amino acids, histidine, serine and threonine, urinary excretion and clearance of glutamic acid, glutamine, glycine and taurine were reduced. Among the different amino acids histidine excretion had the highest variability. Strong correlation was found between the urinary excretion of several amino acids and that of the beta-2-microglobulin characterizing tubular dysfunction. Changes in the excretion of different amino acids reflect the altered metabolic state and renal function due to diabetic ketoacidosis.

ADP-iron as a Fenton reactant: radical reactions detected by spin trapping, hydrogen abstraction, and aromatic hydroxylation

A mixture of ADP, ferrous ions, and hydrogen peroxide (H2O2) generates hydroxyl radicals (OH) that attack the spin trap DMPO (5,5-dimethyl-pyrollidine-N-oxide) to yield the hydroxyl free radical spin-adduct, degrade deoxyribose and benzoate with the release of thiobarbituric acid-reactive material, and hydroxylate benzoate to give fluorescent products. Inhibition studies, with scavengers of the OH radical, suggest that the behavior of iron-ADP in the reaction is complicated by the formation of ternary complexes with certain scavengers and detector molecules. In addition, iron-ADP reacting with H2O2 appears to release a substantial number of OH radicals free into solution. During the generation of OH radicals the ADP molecule was, as expected, damaged by the iron bound to it. Damage to the iron ligand in this way is not normally monitored in reaction systems that use specific detector molecules for OH radical damage. Under certain reaction conditions the ligand may be the major recipient of OH radical damage thereby leading to the incorrect assumption that the iron ligand is a poor Fenton reactant.

Measurement and demonstration of lactase and sucrase activities in jejunal mucosa

Jejunal lactase and sucrase activities were demonstrated on endoscopically obtained biopsy specimens by a rapid test which had been developed earlier. The results were compared with enzyme activities found by Dahlquist's method. The data suggest that the rapid test is suitable for the semiquantitative determination of lactase and sucrase, and the results correlate with enzyme activities measured by the Dahlquist assay. The main advantage of the test is that it is rapid, simple, and cheap, and because no special equipment is necessary, it can be used in any endoscopic department.

[A rapid test for the analysis of lactase and sucrase activity in the jejunum (a comparative study)]

Jejunal lactase and sucrase activities were demonstrated in biopsy specimens obtained endoscopically using a rapid test which had been developed previously. The results were compared with enzyme activities determined by Dahlquist's method. The data suggest that the rapid test is suitable for the demonstration about the presence of lactase and sucrase, and the results are correlated with enzyme activities measured by assay. The main advantage of the test, that it is rapid, simple and cheap, no special equipments are necessary, so it can be used in every endoscopic department.

The effect of CR 1409, a potent CCK receptor antagonist, on basal and stimulated pancreatic secretion in rat

The effect of a specific cholecystokinin (CCK) receptor blocker from Rotta Research Laboratorium (Monza/Milano, Italy), CR 1409 (Lorglumide), on pancreatic secretion was investigated. CR 1409 caused a rightward and parallel shift in the dose-response curve of CCK-8-stimulated pancreatic protein secretion in anesthetized rats, demonstrating a competitive mechanism of inhibition. The mean pA2 value, showing the 50% inhibitory dose of CR 1409, was 6.4. CR 1409 proved to be about 1,000 times more potent as a CCK receptor blocker than proglumide, the first glutaramic acid analogue with anti-CCK potential. In conscious rats, pancreatic protein and water secretion were significantly diminished for about 2 h in response to 300 micrograms/kg of CR 1409 given subcutaneously during diversion of pancreatic juice, demonstrating inhibition of endogenous CCK by this new glutaramic acid derivative. By contrast, during reintroduction of precollected pancreatic juice into the duodenum, when the release of CCK is almost totally eliminated, pancreatic secretion was not modified by the same dose.

Mechanisms of action of alcohol administration on the trophic effect of soybean trypsin inhibitor and cholecystokinin octapeptide in rat

Influence of alcohol administration on the trophic effect of cholecystokinin-octapeptide and soybean trypsin inhibitor administration was examined in male Wistar rats. Two x 4 mL of 20% alcohol given intragastrically during 2 wk did not significantly influence pancreatic weight, DNA, protein, trypsin, chymotrypsin, amylase, lipase, or trypsin inhibitor contents of the pancreas. It diminished the hypertrophy but not the hyperplasia seen after CCK-8 treatment, and eliminated the hyperplasia, as well as the hypertrophy provoked by SBTI administration. Secretory studies and CCK measurements demonstrated decreased CCK release in response to SBTI stimulation after 3-d alcohol administration. The results indicate that alcohol inhibits the enzyme synthesis of the CCK stimulated dividing and/or newly formed acinar cells and the endogenous CCK release.

[Current diagnostic method for saccharose-isomaltose malabsorption]

The authors present the cases of 4 children who suffered from saccharose-isomaltose malabsorption. The clinical symptoms developed following artificial feeding. The diagnosis was made by the histological examination of small intestine samples and with the simultaneous measurement of disaccharide enzyme activity. The histological picture and activity of lactase enzyme were practically normal. The saccharose H2 breath test gave only in 1 case positive result. The treatment of the children required saccharose-free diet. The tolerance showed no improvement during the treatment.

Time-course of changes in pancreatic size and enzyme composition in rats during starvation

The effect of starvation for 3, 5, or 7 d on body weight, fat stores, pancreatic weight, and enzyme composition was studied in 300 g rats and was compared with a 3-d fast in 200 g rats. In the 300 g animals, fasting led to a gradual hypotrophy of the pancreas with a marked, continuous decrease in amylase content. Pancreatic lipase, trypsinogen, chymotrypsinogen, proelastase, and secretory trypsin inhibitor contents increased temporarily, but by d 7, they declined to about the initial values. This decline in enzyme levels coincided with the exhaustion of fat stores. The decrease in amylase content could be related to decreases in circulating insulin levels, whereas the temporary increase in lipase content may be owing to changes in plasma free fatty acid concentrations. In 200 g rats, starvation for 3 d led to exhaustion of fat stores that was accompanied by greater losses of pancreatic weight, protein, and amylase contents. In addition, the levels of trypsinogen and chymotrypsinogen decreased and lipase was unchanged. These findings indicate that during starvation, changes in pancreatic secretory enzymes are time-dependent and vary with the age, body weight, and/or adipose tissue mass of the rats.

Identification of protein-bound riboflavin in rat hepatocyte plasma membrane as a source of autofluorescence

The presence of flavin compound(s) giving a yellowish-green autofluorescence in rat hepatocyte plasma membrane has recently been reported (Nokubo, M. et al. (1988) Biochim. Biophys. Acta 939, 441-448). The fluorophore can quantitatively be extracted with water at 80 degrees C from isolated plasma membranes. Gel filtration of the extract eluted with water showed two peaks, the fluorescence of which closely resembled that of riboflavin. The major peak comigrated with proteins and the minor one displayed a position identical to authentic riboflavin. When the components of the major peak were rechromatographed after acetic acid treatment and eluted with 20 mM of acetic acid, the fluorescent compound separated from the proteins and eluted at the same position as riboflavin. In paper chromatography and HPLC, the behavior of the fluorescent compound (separated by acid treatment from the proteins) was identical to that of riboflavin. SDS gel filtration of subcellular fractions of rat liver revealed that riboflavin was the dominant flavin, whereas FAD and FMN were not detectable in the plasma membrane. Microsomes and mitochondria contain predominantly FAD and FMN, and only minor quantities of riboflavin. The presence of riboflavin in the plasma membrane is a novel finding, the functional significance of which is still unclear; however, a hypothesis can be forwarded on the basis of the ability of flavins to generate superoxide anion radicals during their autoxidation.

[Congenital type I antithrombin III deficiency with serious complications in a 7-year-old girl]

This case report concerns a child admitted to the County Hospital of Zalaegerszeg with the symptoms of ataxia, focal convulsions and hemiparesis. Anticonvulsive therapy abolished the epileptic manifestations, but hemiparesis remained unchanged. At the age of six and half years progressive venous thrombosis developed first on the left and some days later on the right lower limb. Phlebography revealed on both sides thrombosis of the vena iliaca which led to stenosis of the right femoral vein and dilated venous collaterals on the abdomen and right thigh. Coeliacography showed an enlarged spleen and varicosity around the portal vein. Later thrombosis of the arteria dorsalis pedis developed indicated by the gangrene the fifth toe. At this stage the child was transfered to the Pediatric Department of the University of Pécs for further evaluation. Examination of the hemostasis showed hypercoagulability due to antithrombin III deficiency pointing towards a common cause, namely thromboembolism of the earlier and recent clinical manifestations. A reduced activity of the antithrombin III was also observed in the mother and two sisters of the child. The response to Syncumar therapy was beneficial, arterial thrombosis regressed and no further thromboembolic complications developed.

[Two cases of Richter's syndrome]

Two cases of Richter's syndrome were observed by the authors between April and August 1987. The patients were treated previously because of chronic lymphoid leukemia. The histological findings indicated in both cases immunoblast transformation of CLL. The patients were non-respondent to intensive chemotherapy and died within a short time.

Application of a molecular enzyme kinetic model for aging cells and tissues

According to the membrane hypothesis of aging (MHA), cellular senescence is attributable to a life-long, cross-linking action of oxygen-free radicals in the cell plasma membrane, resulting in a continuous decrease of the passive ion permeabilities. The consequent increase in the intracellular potassium content is accompanied by a considerable condensation of the intracellular mass (i.e., by loss of water). MHA suggested that an age-dependent increase in the physical density of the intracellular mass can underly the well-known age-dependent decreases of the macromolecular synthetic processes, the enzymic turnover rates, etc. MHA was partly based on a molecular enzyme kinetic model (MEKM) suggesting that environmental factors can substantially influence the enzyme catalysis and regulation through collisional coupling. However, the possible quantitative ranges of alterations in enzyme activities have not been estimated. This paper concludes, using principal features of the two models, that known age-dependent changes in the membrane lipid fluidity and intracellular density may result in even a 10-fold overall decrease in the enzyme activities (characterized by kcat and k-1) during the life.

Calcium ion uptake, somatotropin release, and fine structure of somatotrophs in cultures of the rat anterior pituitary upon the action of an oligopeptide (Boc-Gln-Leu-Lysinal)

Cultured cells from the anterior pituitary glands of adult rats were treated with the tripeptide aldehyde proteinase inhibitor, Boc-Gln-Leu-Lys-H. The oligopeptide had a profound releasing effect on growth hormone, whereas the prolactin release remained unchanged at 10(-3) mol/l drug concentration after an incubation for 2 h. In the presence of the oligopeptide a time- and dose-dependent calcium influx into cultured cells has been shown which was proved to be almost completely antagonized with magnesium ions but not with Nifedipine. In addition, radioactive calcium ions could be detected in a number of cells by light microscopic autoradiography when cultures were treated with Boc-Gln-Leu-Lys-H for short periods. The selective Gel action of the oligopeptide on growth hormone producing cells has been demonstrated also in fine structural investigations: multigranular and single exocytotic profiles have been observed. Accordingly, we have postulated that Boc-Gln-Leu-Lysinal mimics the effects of the known ionophores. Its mode of action needs, however, further studies especially on isolated somatotrophs.

Spatial distribution of pre- and postsynaptic sites of axon terminals in the dorsal horn of the frog spinal cord

Axon terminals which could be interpreted as dorsal root boutons, were photographed from a series of 98 ultrathin sections with a Jeol 100B electron microscope. A total of 13 boutons were recovered for computer reconstruction. Two of them were terminal boutons, eight en passant boutons and three boutons were only partially recovered. All boutons contained multiple synaptic sites (maximum 33 and minimum seven) at which axodendritic and axoaxonic synapses were established. Axodendritic synapses were of the asymmetric type and they were directed toward adjacent dendrites. In axoaxonic synapses, which were of the symmetric type, the boutons were invariably on the postsynaptic side. Among the presynaptic profiles axons with spherical and pleomorphic vesicles and dendrites with flattened vesicles could be discerned. On average, each 2.67-microns2 bouton surface area contained one presynaptic site at which an axodendritic synapse was established, and each 7-microns2 surface area contained one postsynaptic site for an axoaxonic (or dendroaxonic) contact. A tendency of grouping of synaptic sites was observed. Distance measurements between the closest neighbours of all synaptic sites were made in four combinations in boutons with the original and with a random distribution of synaptic sites. The arithmetic mean of distances measured between the presynaptic and the closest postsynaptic sites was almost twice as big as that measured in the reverse direction. The difference between these values became greatly reduced in the case of random distribution. The arithmetic mean of distances between the closest neighbours of presynaptic sites was about the same as that between the closest neighbours of postsynaptic sites. This latter value was considerably increased with randomly distributed synaptic sites. The results suggest a non-random distribution of synaptic sites on the surface of boutons. The analysis of cluster formation of synaptic sites performed with a numerical taxonomy technique revealed that the majority of the 153 synaptic sites were comprised in 27 clusters containing both pre- and postsynaptic sites within the 1-micron similarity level. All postsynaptic sites were within 1 micron of one or more presynaptic sites. On the basis of the assumption that the postsynaptic sites are occupied by inhibitory axoaxonic synapses, it is suggested that the transmitter release from the presynaptic sites can be individually controlled in this structural arrangement. A probable mechanism of this function may be the passive invasion of the bouton by the impulse propagating actively along the dorsal root fibre.

The anti-CCK effect of glutaramic acid derivatives in anesthetized and conscious rats

The effects of specific gastrin-cholecystokinin (CCK) receptor blockers (proglumide and a new, more potent product of Rotta Research Laboratorium, CR-1392) on pancreatic secretion were studied. Proglumide and CR-1392 caused a rightward and parallel shift, respectively, in the dose-response curve of CCK8 stimulated pancreatic protein secretion in anesthetized rats, demonstrating a competitive-like mechanism of inhibition. The mean PA2 values, demonstrating the 50% inhibitory dose of proglumide and CR-1392 were 3.7 and 5.7, respectively; i.e., CR-1392 proved to be about 100 times more potent than proglumide. In conscious rats, protein output and the volume of pancreatic juice were significantly decreased for about 2 h in response to 150 mg/kg of proglumide or 3 mg/kg of CR-1392 administered s.c. during diversion of pancreatic juice, demonstrating inhibition of endogenous CCK by glutaramic acid derivatives. Indeed, during reintroduction of precollected pancreatic juice into the duodenum, when the release of CCK is known to be almost totally eliminated, pancreatic secretion was not significantly modified by the same doses.

The tripeptide aldehyde, Boc-DPhe-Phe-Lysinal, is a novel Ca2+ channel inhibitor in pituitary cells

The effect of Boc-DPhe-Phe-Lysinal (Boc-DPPL) on the 45Ca2+ uptake of rat anterior pituitary monolayer cultures was investigated. The compound decreased the basal Ca2+ uptake at 3 x 10(-4) mol/l. The 45Ca2+ uptake stimulated by potassium-induced depolarization was more sensitive to Boc-DPPL inhibition, a slight decrease was seen with 3 x 10(-6) mol/l and there was a half maximal inhibition at 3 x 10(-5) mol/l. Boc-DPPL is known to inhibit pituitary hormone release in similar concentrations, an effect might also be due to its calcium antagonist property.

Effect of perfringolysin O on the lateral diffusion constant of membrane proteins of hepatocytes as revealed by fluorescence recovery after photobleaching

Perfringolysin O is a thiol-activated cytolytic exotoxin the primary receptor of which is the membrane cholesterol on the cell surface. The effect of perfringolysin O was tested in various hepatocyte preparations. (i) Smears of fresh liver exposed to a mild H2O2 (1.0 mM) injury for 10 min at 37 degrees C, develop a 'peroxide-induced autofluorescence' (PIAF) on the membrane proteins. PIAF is suitable for measuring the average lateral diffusion constant (D) of the membrane proteins by means of fluorescence recovery after photobleaching technique (FRAP). Incubation for 5 min with 600 or 2000 units/ml of the perfringolysin O resulted in a significant increase (32 and 46%, respectively) of D as compared to the controls of the same age group (13-14 months). Various tests like heat denaturation of cholesterol saturation of perfringolysin O before its application as well as thiol-activation of the smears with dithiothreitol revealed that the increase of D is a specific toxin effect due mot probably to the reaction of perfringolysin O with cholesterol. (ii) Isolated hepatocytes were exposed to perfringolysin O and their viability as well as the release of two cytosolic enzymes (lactate dehydrogenase and glutamic-pyruvic transaminase) were measured; 40-60 units/ml of perfringolysin O in 30 min reduced the viability of the hepatocytes to zero and caused a release of about 70% of both cytosolic enzymes. The significance of the results is discussed from the points of view of both the toxin-effect and the FRAP method.

Characterization of the autofluorescence of rat liver plasma membranes

The autofluorescence of isolated rat liver cell plasma membranes was characterized in vitro in relation to the autofluorescence used previously for fluorescence recovery after photobleaching (FRAP) studies. The fluorescence of membrane preparations displayed an emission pattern with a maximum at around 525 nm when excited with a 468 nm blue light. The excitation spectrum monitored at 525 nm closely resembled that of flavin compounds (riboflavin, FAD, FMN). The chloroform extract of the membrane fraction showed practically no fluorescence, whereas, both the water-soluble and water-insoluble protein fractions remaining after chloroform extraction were strongly fluorescent. The fluorescence disappeared almost completely under the effect of sodium hydrosulfite, and recovered after oxidation either by shaking in air or by adding buffered hydrogen peroxide solution. The fluorescence of the acid extract of the plasma membranes photolyzed in an alkaline medium was quite similar to that of lumiflavin obtained from the photolysis of riboflavin in an alkaline medium. The plasma membranes prepared from isolated hepatocytes (which were completely devoid of endothelial cell contamination) exhibited the same autofluorescence in the liver cell plasma membranes. The results suggest that the autofluorescence of the liver cell plasma membranes is most likely of a character similar to that of flavin, bound to hepatocyte plasma membrane proteins. This fluorescence is suitable for measuring the average lateral diffusion constant of proteins by means of FRAP methods.

The bulk specimen X-ray microanalysis of freeze-fractured, freeze-dried tissues in gerontological research

The rationale for choosing the freeze-fracture freeze-drying (FFFD) method of biological bulk specimen preparation as well as the theoretical and practical problems of this method are treated. FFFD specimens are suitable for quantitative X-ray microanalysis of biologically relevant elements. Although the spatial resolution of this analytical technique is low, the application of properly selected bulk standard crystals as well as the measurement of the intracellular water and dry mass content by means of another method developed in the same laboratory, allow us to obtain useful information about the age-dependent changes of ionic composition in the main intracellular compartments. The paper summarizes the problems with regard to specimen preparation, beam penetration and the quantitative analysis of FFFD specimens. The method has been applied so far mainly for the analysis of intranuclear and intracytoplasmic concentrations of Na, C1 and K in various types of cells and has resulted in a significant contribution to our understanding of the cellular mechanisms of aging.

Age dependent dehydration of postmitotic cells as measured by X-ray microanalysis of bulk specimens

In this paper we give a brief outline of our bulk specimen technique developed to measure intracellular water concentration in frozen-hydrated biological specimens by means of energy dispersive X-ray microanalysis. Fractured surface of the deep-frozen tissue samples is analyzed in an electron microscope (a specimen area of 15 x 11.5 micron is scanned) using 20 kV accelerating voltage and 1-5 pA effective beam current (measured in the specimen). Strong electric charging, which is the main problem associated with the low temperature X-ray microanalysis of frozen-hydrated specimens, is reduced by choosing optimum temperature range for the measurements (170-185 K) and by etching a thin surface layer on specimen surface. The main advantage of the method over other X-ray microanalytical techniques using sections and bulk specimens for water and dry-mass content determinations in cells (which are shortly reviewed) is the simple specimen preparation, the easy sample handling and the good stability of specimen during measurements. The main disadvantage is the poor spatial resolution as compared to the analysis of sections. Measurements with our method provided meaningful results of the change in intracellular water contents in various postmitotic cells of rats dependent on age. The observed decline of the intracellular water contents results in increased ionic strength and slower diffusion in old cells than in young ones. These effects may be implicated in senescent deterioration of cell metabolism.

The effect of OH(.) radicals generated by Fenton reaction on the growth and cartilage differentiation in limb bud cell culture

A consistent chondrogenesis takes place in micro high-density cultures of chick limb bud mesenchyme cells stage 22-24. The effect of an increased generation of OH(.) free radicals by Fenton reaction was tested in these cultures. Components of Fenton reaction (i.e., ferrous iron in form of ADP-Fe2+ complex in 0.1 mM concentration, or 0.2 mM H2O2, or the combination of these components with each other, as well as with 0.2 mM ascorbate) were supplemented to the culture medium after the first 24 h. ADP-Fe2+ complex resulted in a drastic decrease of the frequency and confluence of the cartilage nodules seen in light microscope, accompanied electron microscopically by a strikingly increased frequency of occurrence of lipofuscin-like, residual bodies in the cells. Biochemical methods revealed a significant decrease of both the DNA and glycosaminoglycan contents (to 48.6 and 20.7% of the controls, respectively), in day 6 cultures. H2O2 alone caused similar alterations of the cultures, whereas the combination of it with ADP-Fe2+ complex proved to be lethal for the cells. Ascorbate when added to the ADP-Fe2+-treated cultures displayed a slight protective effect for the glycosaminoglycan content but not for DNA. The results are interpreted in terms of free radical theory of aging.

Energy-dispersive, bulk specimen X-ray microanalytical measurement of the intracellular Na+/K+ ratio in human laryngeal tumors

Energy-dispersive X-ray microanalysis was performed on human biopsy materials taken during laryngoscopic intervention in 18 cases. The removed tissue pieces were divided into two parts. One of them was used for pathohistological studies, the other was processed for X-ray microanalysis by the freeze-fracture freeze-drying method. Of the cases investigated 4 proved to be of benign character, whereas the rest contained carcinoma planocellulare keratoides or non-keratoides. Bulk specimen energy-dispersive X-ray microanalysis of 135 cells from the benign tissue samples revealed an average Na+/K+ molar ratio of 0.13 +/- 0.01 (SEM) in the intracellular space, with a regular Gaussian distribution. In the cases of carcinomas 641 cells were measured, the average of the same ratio was 0.67 +/- 0.03 (SEM) due mostly to an increase in the Na+ content. The distribution of data was apparently not normal in the cancerous samples. These observations and some theoretical considerations support the notion that the intracellular Na+/K+ ratio correlates with the proliferative capacity of tissues. The relevance of some recent biochemical results is also discussed in this respect.

Memorial lecture: Verzár's ideas on the age-dependent protein cross-linking in the light of the present knowledge

This lecture was aimed to commemorate the centenary of the birthday (18 September 1886) of Fritz Verzár, one of the most important European founders of experimental gerontology. He was an exceptionally creative scientist who contributed considerably to the development of physiology in this century: he achieved important results in the fields of intestinal absorption, in the adrenal gland's function, and finally, from 1952 until his death (1979), he was creator, promotor and one of the best leaders of experimental gerontology. His idea about the age-dependent cross-linking of protein molecules as a general cause of cell aging--studied by him mainly using the collagen as a model, however, extended also to the nucleoproteins--was a pioneer's work. Yet, its significance was not immediately recognized, the contemporary scientists could not interpret his thoughts in the terms of test-tube biochemistry. However, about a decade later, in the sixties and afterwards, an increasing body of evidence has been accumulated indicating that Verzár was right: the most general age-dependent alteration of the proteins in the living systems known so far is a posttranslational modification of their structure and conformation due to the aggressive effects of the oxygen free radicals. Consequences of these thoughts are being realized nowadays in theory and practice. The present generation of scientists expresses its respect and recognition to Fritz Verzár whose life and activity have been teaching us that aging can be understood, if we find the proper theoretical approach to it.