50-kb chromatin fragmentation in the absence of apoptosis

Treatment with ionic detergents of nuclei isolated from various continuously growing cell lines generally yields chromatin samples of high viscosity. Extensive treatment with nuclease-free proteinase K or pronase solubilized the viscous lysates with > 90% of the DNA migrating at approximately 50 kb. Freshly prepared human peripheral blood T cells also yield a substantial fraction of their DNA in an approximately 50- to 100-kb band. The cleavage sites may coincide with a class of DNase I-hypersensitive regions, since digestion of chromatin by DNase I at approximately 10 U/ml, without protease, also yields fragments of preferentially approximately 50-kb size. Occasionally, the oligonucleosomal ladder was also detected together with high molecular weight degradation products. Remarkably, all of these fragmentation patterns were seen in healthy, resting or proliferating cells, i.e., in the absence of apoptosis. Tritiated thymidine incorporation could be readily detected in the approximately 50-kb DNA fragments. The effect of an apoptotic intracellular milieu on the integrity of isolated chromatin is apparently imitated by the extensive protease treatment used in our DNA isolation protocol.

Effects of calcitonin gene-related peptide on acute and chronic effects of morphine

Calcitonin gene-related peptide (CGRP), which has been observed in different parts of the nervous system, is known to modify pain sensitivity to different stimuli in rats and mice. The aim of this study was to investigate the possible interaction of CGRP with morphine on nociception in adult male NMRI mice after central administration of the peptide. CGRP (20 or 200 ng) did not itself modify pain sensitivity in the tail-flick test and did not affect the acute antinociceptive action of a single dose of morphine in the same test. However, CGRP suppressed the development of rapid tolerance to morphine in a dose-dependent manner, but had no action on the development of chronic tolerance to morphine and on manifestations of naloxone-precipitated withdrawal syndrome.

Isolation and characterization of the catalytic subunit of protein phosphatase 2A from Neurospora crassa

The catalytic subunit of protein phosphatase 2A (PP2Ac) was purified from Neurospora crassa extract by (NH4)2SO4-ethanol precipitation followed by DEAE-Sephacel, heparin-Sepharose, and MonoQ chromatography steps about 900-fold to a specific activity of 1200 U/g with a 2% yield. The apparent M(r) of PP2Ac was estimated to be 35 kDa by gel filtration and 33 kDa by SDS polyacrylamide gel electrophoresis. Half maximal inhibition of PP2Ac was achieved at 0.3 nM okadaic acid, 0.1 nM microcystin-LR, 56 nM cantharidin and 280 nM endothall concentrations. The preparation was completely inhibited by 20 mM NaF, was insensitive to rabbit muscle inhibitor-2, and was specific for the alpha-subunit of rabbit muscle phosphorylase kinase. According to its biochemical properties, N. crassa PP2Ac is very similar to its mammalian counterparts. Antipeptide antibodies raised against the N-terminal and C-terminal ends of human PP2Ac did not cross-react with N. crassa PP2Ac, indicating sequence differences outside the catalytic core of the enzyme.

Oxytocin blocks the development of heroin-fentanyl cross-tolerance in mice

The development of cross-tolerance to an analgesic effect was observed between two mu-receptor agonists, heroin and fentanyl. Repeated treatments with heroin twice a day for 4 days resulted in a decreased nociceptive effect to fentanyl on day 5. The fentanyl dose-response line shifted to the right, and was considered to be a sign of the development of cross-tolerance. Peripheral treatment with oxytocin did not block the development of heroin-fentanyl cross-tolerance. However, intracerebroventricular administration of oxytocin blocked the development of tolerance, causing a leftward shift in the dose-response curve and supporting the assumption that oxytocin blocks the development of heroin-fentanyl cross-tolerance via CNS mechanisms.

[Bonding strength and fracture resistance of artificial teeth in dental prostheses]

Debonding of plastic teeth from its denture base has been frequently experienced in our prosthetic practice. Three of nine products investigated have fulfilled the requirements for bonding according to ISO test 3336. Loading forces necessary to produce fractures varied between 170-810 N within the tooth and 80-230 N at the tooth-denture base interface. Comparative significances were noted for the mean breaking force against fracture and debonding when comparing the resistance of "Acry Rock" to the other eight materials tested. Maximizing the extension of the polymerization surface through a larger surface area of individual teeth seemed to be a significant factor in the determination of the debonding force necessary to produce fracturing.

Expression of protein kinase C family members in the cerebral endothelial cells

The protein kinase C (PKC) family is composed of at least four conventional (alpha, beta I, beta II, and gamma) and several related novel (delta, epsilon, eta, and zeta) isoforms with different distribution and sensitivity to Ca2+ and phorbol esters. The enzyme is known to be present in cerebral endothelial cells. We have investigated the occurrence of seven isoforms (alpha, beta, gamma, delta, epsilon, eta, and zeta) by using reverse transcriptase-polymerase chain reaction in rat brain, in a freshly isolated brain microvessel fraction, in primary cultures of rat brain endothelial cells, in an immortalized rat brain endothelial cell line, and in aortic endothelial cell cultures. Brain tissue contained all seven investigated isoforms. A similar expression pattern was seen in freshly purified microvessels, but the PKC-gamma isoform could not be detected. Primary cultures of endothelial cells expressed PKC-alpha, -beta, -delta, -eta, and -epsilon isoenzymes, whereas the immortalized cell line expressed PKC-alpha, -delta, -epsilon, and -eta. The rat aortic endothelium contained only PKC-alpha and -delta isoforms. The variety of expression patterns of PKC family members in endothelial cells of different type may reflect differences in the functional responsiveness to environmental stimuli. Because PKC has been shown to be involved in the regulation of the blood-brain barrier permeability, the presence of different isoforms may confer a sophisticated intracellular regulatory mechanism to the brain endothelial cells.

Effects of secretin on acute and chronic effects of morphine

The effects of intracerebroventricularly (ICV) administered secretin on the analgesic, tolerance-inducing, and dependence-inducing actions of morphine were investigated, in adult, male CFLP mice. Secretin administered doses ICV did not itself affect pain sensitivity in a heat-radiant tail flick test. However, it depressed the acute nociceptive effect of a single subcutaneous (SC) dose of morphine (4 mg/kg) after ICV (1 or 10 ng/animal) secretin administration. A dose of 10 ng secretin facilitated the development of acute morphine tolerance. On the other hand, none of the doses applied had any influence on chronic morphine tolerance, where animals were implanted SC with a morphine- containing pellet and the pain sensitivity was measured 3 days later. Morphine withdrawal signs were also evaluated by injecting naloxone. In a 100-ng dose, secretin increased the latency of the withdrawal jumping response; the peptide did not modify the other abstinence signs. These data suggest that central secretin administration can modify the analgesic effect of morphine.

Airflow resistance monitoring in laryngotracheal stenosis. Laser surgery in bilateral vocal cord paralysis

Thirty-seven patients with laryngotracheal stenosis were treated within the last 3 years at the ENT Department of the Semmelweis University of Medicine in Budapest. Unilateral laser arytenoidectomy was performed in the group with pure vocal cord paralysis. Airflow resistance of the upper respiratory tract was measured with a modified Rhinotest MP 500 active anterior rhinomanometer through the tracheostomal orifice before and after the operation. The mean preoperative resistance was 0.951 Pa/cm3/s, which was reduced to 0.487 Pa/cm3/s postoperatively. In the successfully decannulated cases the postoperative resistance value averaged 0.360 Pa/cm3/s. The resistance limit (including nasal and pharyngeal resistances) seems to be 0.50 Pa/cm3/s.

[Insulin concentration in amniotic fluid in mid-term pregnancy]

Insulin concentrations of 284 amniotic fluid samples were assessed, obtained from pregnant women by genetic amniocentesis between the 16-18 gestational weeks. The indication of amniocentesis was either advanced maternal age (> 35 years) or high risk genetic history. The amniotic fluid insulin concentration (mean +/- SD) was found 3.8 +/- 3.0 microIU/ml. The insulin concentration in 4.3% of all pregnant women was higher than the mean value +2 SD (9.8 microIU/ml) which represents individual pathological value, characteristic for gestational diabetes. Our data suggest that one part of gestational diabetes might be detected between the 16-18 gestational weeks, therefore we propose an earlier screening as the usual one. At institutes where the possibility of genetic amniocentesis is given the determination of insulin level in amniotic fluid may be reasonable. We could analyze the outcome of 230 pregnancies analysed. A close correlation was found between the amniotic fluid insulin concentration and birthweights of female newborns. It could not found such correlation at male newborn. A more careful screening test for gestational diabetes should be performed at mothers with female fetuses.

Cross-linking of CD4 in a TCR/CD3-juxtaposed inhibitory state: a pFRET study

Instances when T cell activation via the T cell receptor/CD3 complex is suppressed by anti-CD4 Abs are generally attributed either to the topological separation of CD4-p56lck from CD3, or their improper apposition. Photobleaching fluorescence resonance energy transfer measurements permitted direct analysis of these alternatives on human peripheral blood lymphocytes. Distinction between changes of relative antigen densities or positioning was made possible by simultaneously recording donor and acceptor fluorescence in the energy transfer experiment performed on homogeneous populations of flow-sorted cells. We show here that CD4 stays in the molecular vicinity of CD3, while anti-CD3 stimulation is suppressed by anti-CD4 or cross-linked HIV gp120. Our data suggest that cross-linking of CD4 through particular epitopes is capable of inhibiting activation driven by Abs binding to specific sites on CD3 without major topological sequestration of the Ags, in such a way that additional positive signals will also be affected. Thus, these and other related cases of negative signaling via CD4 may be interpreted in terms of functional uncoupling rather than a wide physical separation of CD4 from the T cell receptor-CD3 complex.

[Possibilities for improvement of the surface properties of dental implants (2). The use of ceramic oxides in surface coating for titanium and tantalum implants]

A corrosion-resistant, 2000-2500 A thick, ceramic oxide layer with a coherent crystalline structure was produced on the surface of titanium implants. The layer contains a bioactive component, it is made from the material of the implant, adheres well and gives an aesthetically pleasant impression. The coated implants were subjected to various physical, chemical electronmicroscopic, etc. tests for their qualitative characterization. These tests demonstrated the good properties of the implants. The procedure is protected internationally by patents.

DNA uptake stimulating protein from Neurospora crassa enhances DNA and oligonucleotide uptake also in mammalian cells

The presence of the DNA uptake stimulating protein (designated earlier as DUSF by Schablik and Szabó (1981) FEMS Microbiol. Lett. 10, 395-397) was demonstrated on the surface of Neurospora crassa (FGSC 1118, slime) fungal cells as well as on HEp-2 and K562 human and F4N mouse tumor cells by immunofluorescence microscopy. DUSF markedly enhanced the uptake of both macromolecular [3H]DNA and of [3H]oligonucleotides by K562, HL-60 and also by DD human leukemia cells. Polyclonal anti-DUSF antibodies inhibited both the basal and stimulated [3H]oligonucleotide uptake by K562 cells. DNA-DNA hybridization has shown that the uptake of linearized pBR322 plasmid DNA into N. crassa and K562 cells was stimulated by DUSF, increasing proportionally with the length of incubation time. Unfragmented plasmid molecules were recovered from the cells. It is assumed that DUSF (or related proteins) may play a role in the physiological uptake of oligonucleotides and DNA not only in N. crassa but also in--at least some--mammalian cells.

[Possibilities of improving surface properties of medical implants 1]

The work is planned in three parts. The first reviews the various modification of the surface-treatment procedures for medical implants. A separate section deals with procedures involving the application of material or the removal of material, and those is which material is not applied or removed. Special consideration is paid to the surface-treatment procedures for facial or mandibular implants, and techniques involving calcium phosphate and hydroxylapatite coatings.

The role of central corticoliberin in the hyperosmosis-induced secretion of neurohypophysial hormones and corticosterone in the rat

Although synthetic corticotropin-releasing hormone (CRH) is known to influence the secretion of the neurohypophysial hormones, the role of endogenous CRH in the rat brain is still unclear in this respect. Accordingly, experiments were scheduled to study the effects of intracerebroventricularly (i.c.v.) administered CRH-antiserum (AS) on the hyperosmosis-induced secretion of arginine-8-vasopressin (AVP), oxytocin (OXT) and corticosterone in Wistar male rats. A 2 microliters CRH-AS injection was given, and repeated 24 h later, 30 min prior to intraperitoneal administration of hypertonic saline (HS; 2.5% NaCl, 2 ml/100 g body weight) followed by decapitation in 15 min. Plasma AVP and OXT were measured by radioimmunoassay and corticosterone by fluorimetry. HS increased the levels of AVP, OXT and corticosterone. CRH-AS did not change the plasma concentrations of these hormones in 0.9% NaCl-treated animals. CRH-AS pretreatment prevented the corticosterone-releasing action of HS, and significantly moderated the HS-induced AVP and OXT increase. These findings suggest that the central CRH system may participate in the regulation of corticosterone and neurohypophysial hormone secretion evoked by acute osmotic challenge.

[Water absorption and water solubility of prosthetic materials]

Denture base materials investigated with using surface coating polymers fulfilled requirements of ISO Standards 1567 for water sorption and water solubility. The heat-cured polymer gave up water in a greater extent comparing to the cold-cured one. Further amount of water was retained by the surface treatment of coating. A five times increase of water solubility in samples of cold-cured resin was found comparing to the heat-cured ones. A significant decrease of water sorption was measured by using the surface coating.