Structural determinants governing S100A4-induced isoform-selective disassembly of nonmuscle myosin II filaments

The Ca(2+) -binding protein S100A4 interacts with the C terminus of nonmuscle myosin IIA (NMIIA) causing filament disassembly, which is correlated with an increased metastatic potential of tumor cells. Despite high sequence similarity of the three NMII isoforms, S100A4 discriminates against binding to NMIIB. We searched for structural determinants of this selectivity. Based on paralog scanning using phage display, we identified a single position as major determinant of isoform selectivity. Reciprocal single amino acid replacements showed that at position 1907 (NMIIA numbering), the NMIIA/NMIIC-specific alanine provides about 60-fold higher affinity than the NMIIB-specific asparagine. The structural background of this can be explained in part by a communication between the two consecutive α-helical binding segments. This communication is completely abolished by the Ala-to-Asn substitution. Mutual swapping of the disordered tailpieces only slightly affects the affinity of the NMII chimeras. Interestingly, we found that the tailpiece and position 1907 act in a nonadditive fashion. Finally, we also found that the higher stability of the C-terminal coiled-coil region of NMIIB also discriminates against interaction with S100A4. Our results clearly show that the isoform-selective binding of S100A4 is determined at multiple levels in the structure of the three NMII isoforms and the corresponding functional elements of NMII act synergistically with one another resulting in a complex interaction network. The experimental and in silico results suggest two divergent evolutionary pathways: NMIIA and NMIIB evolved to possess S100A4-dependent and -independent regulations, respectively.

Discrete molecular dynamics can predict helical prestructured motifs in disordered proteins

Intrinsically disordered proteins (IDPs) lack a stable tertiary structure, but their short binding regions termed Pre-Structured Motifs (PreSMo) can form transient secondary structure elements in solution. Although disordered proteins are crucial in many biological processes and designing strategies to modulate their function is highly important, both experimental and computational tools to describe their conformational ensembles and the initial steps of folding are sparse. Here we report that discrete molecular dynamics (DMD) simulations combined with replica exchange (RX) method efficiently samples the conformational space and detects regions populating α-helical conformational states in disordered protein regions. While the available computational methods predict secondary structural propensities in IDPs based on the observation of protein-protein interactions, our ab initio method rests on physical principles of protein folding and dynamics. We show that RX-DMD predicts α-PreSMos with high confidence confirmed by comparison to experimental NMR data. Moreover, the method also can dissect α-PreSMos in close vicinity to each other and indicate helix stability. Importantly, simulations with disordered regions forming helices in X-ray structures of complexes indicate that a preformed helix is frequently the binding element itself, while in other cases it may have a role in initiating the binding process. Our results indicate that RX-DMD provides a breakthrough in the structural and dynamical characterization of disordered proteins by generating the structural ensembles of IDPs even when experimental data are not available.

Acute escitalopram treatment inhibits REM sleep rebound and activation of MCH-expressing neurons in the lateral hypothalamus after long term selective REM sleep deprivation

RATIONALE

Selective rapid eye movement sleep (REMS) deprivation using the platform-on-water ("flower pot") method causes sleep rebound with increased REMS, decreased REMS latency, and activation of the melanin-concentrating hormone (MCH) expressing neurons in the hypothalamus. MCH is implicated in the pathomechanism of depression regarding its influence on mood, feeding behavior, and REMS.

OBJECTIVES

We investigated the effects of the most selective serotonin reuptake inhibitor escitalopram on sleep rebound following REMS deprivation and, in parallel, on the activation of MCH-containing neurons.

METHODS

Escitalopram or vehicle (10 mg/kg, intraperitoneally) was administered to REMS-deprived (72 h) or home cage male Wistar rats. During the 3-h-long "rebound sleep", electroencephalography was recorded, followed by an MCH/Fos double immunohistochemistry.

RESULTS

During REMS rebound, the time spent in REMS and the number of MCH/Fos double-labeled neurons in the lateral hypothalamus increased markedly, and REMS latency showed a significant decrease. All these effects of REMS deprivation were significantly attenuated by escitalopram treatment. Besides the REMS-suppressing effects, escitalopram caused an increase in amount of and decrease in latency of slow wave sleep during the rebound.

CONCLUSIONS

These results show that despite the high REMS pressure caused by REMS deprivation procedure, escitalopram has the ability to suppress REMS rebound, as well as to diminish the activation of MCH-containing neurons, in parallel. Escitalopram caused a shift from REMS to slow wave sleep during the rebound. Furthermore, these data point to the potential connection between the serotonergic system and MCH in sleep regulation, which can be relevant in depression and in other mood disorders.

The highly conserved, N-terminal (RXXX)8 motif of mouse Shadoo mediates nuclear accumulation

The prion protein (PrP)-known for its central role in transmissible spongiform encephalopathies-has been reported to possess two nuclear localization signals and localize in the nuclei of certain cells in various forms. Although these data are superficially contradictory, it is apparent that nuclear forms of the prion protein can be found in cells in either the healthy or the diseased state. Here we report that Shadoo (Sho)-a member of the prion protein superfamily-is also found in the nucleus of several neural and non-neural cell lines as visualized by using an YFP-Sho construct. This nuclear localization is mediated by the (25-61) fragment of mouse Sho encompassing an (RXXX)8 motif. Bioinformatic analysis shows that the (RXXX)n motif (n=7-8) is a highly conserved and characteristic part of mammalian Shadoo proteins. Experiments to assess if Sho enters the nucleus by facilitated transport gave no decisive results: the inhibition of active processes that require energy in the cell, abolishes nuclear but not nucleolar accumulation. However, the (RXXX)8 motif is not able to mediate the nuclear transport of large fusion constructs exceeding the size limit of the nuclear pore for passive entry. Tracing the journey of various forms of Sho from translation to the nucleus and discerning the potential nuclear function of PrP and Sho requires further studies.

Epidemiological modelling of risk factors of human papilloma virus in women with positive cytology in the county of Csongrád

This study was carried out to determine the prevalence and risk factors of genital HPV infection in women diagnosed with non-negative cytology in Southeastern Hungary. Cervical samples were collected for cytology and HPV testing from women seen at gynaecological outpatient clinics and diagnosed with non-negative cytology. The observed overall average HPV infection rate was found to be 61%. A smoking habit was the only risk factor in the logistic regression analysis that related significantly to exposure to HPV infection. Thus, prevention strategies should focus on the regular clinical cytological screening of HPV-infected patients and on the reduction of smoking.

TOPDOM: database of domains and motifs with conservative location in transmembrane proteins

Summary: The TOPDOM database is a collection of domains and sequence motifs located consistently on the same side of the membrane in α-helical transmembrane proteins. The database was created by scanning well-annotated transmembrane protein sequences in the UniProt database by specific domain or motif detecting algorithms. The identified domains or motifs were added to the database if they were uniformly annotated on the same side of the membrane of the various proteins in the UniProt database. The information about the location of the collected domains and motifs can be incorporated into constrained topology prediction algorithms, like HMMTOP, increasing the prediction accuracy.

Availability: The TOPDOM database and the constrained HMMTOP prediction server are available on the page http://topdom.enzim.hu

Contact:tusi@enzim.hu; lkalmar@enzim.hu

TOPDB: topology data bank of transmembrane proteins

The Topology Data Bank of Transmembrane Proteins (TOPDB) is the most complete and comprehensive collection of transmembrane protein datasets containing experimentally derived topology information currently available. It contains information gathered from the literature and from public databases available on the internet for more than a thousand transmembrane proteins. TOPDB collects details of various experiments that were carried out to learn about the topology of particular transmembrane proteins. In addition to experimental data from the literature, an extensive collection of structural data was also compiled from PDB and from PDBTM. Because topology information is often incomplete, for each protein in the database the most probable topology that is consistent with the collected experimental constraints was also calculated using the HMMTOP transmembrane topology prediction algorithm. Each record in TOPDB also contains information on the given protein sequence, name, organism and cross references to various other databases. The web interface of TOPDB includes tools for searching, relational querying and data browsing as well as for visualization. TOPDB is designed to bridge the gap between the number of transmembrane proteins available in sequence databases and the publicly accessible topology information of experimentally or computationally studied transmembrane proteins. TOPDB is available at http://topdb.enzim.hu.

HAEdb: a novel interactive, locus-specific mutation database for the C1 inhibitor gene

Hereditary angioneurotic edema (HAE) is an autosomal dominant disorder characterized by episodic local subcutaneous and submucosal edema and is caused by the deficiency of the activated C1 esterase inhibitor protein (C1-INH or C1INH; approved gene symbol SERPING1). Published C1-INH mutations are represented in large universal databases (e.g., OMIM, HGMD), but these databases update their data rather infrequently, they are not interactive, and they do not allow searches according to different criteria. The HAEdb, a C1-INH gene mutation database (http://hae.biomembrane.hu) was created to contribute to the following expectations: 1) help the comprehensive collection of information on genetic alterations of the C1-INH gene; 2) create a database in which data can be searched and compared according to several flexible criteria; and 3) provide additional help in new mutation identification. The website uses MySQL, an open-source, multithreaded, relational database management system. The user-friendly graphical interface was written in the PHP web programming language. The website consists of two main parts, the freely browsable search function, and the password-protected data deposition function. Mutations of the C1-INH gene are divided in two parts: gross mutations involving DNA fragments >1 kb, and micro mutations encompassing all non-gross mutations. Several attributes (e.g., affected exon, molecular consequence, family history) are collected for each mutation in a standardized form. This database may facilitate future comprehensive analyses of C1-INH mutations and also provide regular help for molecular diagnostic testing of HAE patients in different centers.

Asymmetric PCR increases efficiency of melting peak analysis on the LightCycler

OBJECTIVES

To systematically analyze the effects of asymmetric PCR on LightCycler melting analyses of four different allelic-discrimination systems and to reduce an inconsistent non-specific melting peak observed during factor V Leiden genotyping.

DESIGN AND METHODS

PCR amplifications and melting analyses were carried out with various oligonucleotide concentrations and ratios. To monitor the efficiency, calculated peak area values were compared after melting analyses.

RESULTS

Peak area values increased by a mean of 11.2-fold (range: 6 to 17) in case of an amplification primer ratio of 1:6.7 asymmetric PCR compared to symmetric primer conditions in four different SNP-genotyping systems. Using a complementary hybridization probe set for factor V Leiden genotyping, a converse amplification primer ratio was necessary for similar results.

CONCLUSIONS

Asymmetric PCR resulting in the formation of higher amounts of target strands significantly increases the efficiency of LightCycler allelic-discrimination.

Frequencies of two common mutations (c.35delG and c.167delT) of the connexin 26 gene in different populations of Hungary

The most common form of non-syndromic autosomal recessive deafness (NSRD) is caused by mutations in the gene GJB2, encoding the protein connexin 26 (Cx26). The mutation c.35delG is found in 30-70% of Caucasian NSRD cases, and is abundant (allele frequency of 0.5-2%) in several European populations, while c.167delT is found in the Ashkenazi Jewish population with about 2% frequency. In the current study, using simple PCR-based tests we established an allele frequency of 0.6% in the Hungarian average, and 0.4% in the Romani (Gypsy) populations for the c.35delG mutation, and an allele frequency of 2.4% in the Ashkenazi population for the c.167delT mutation. Our results do not differ significantly from the published data for Caucasian and non-European Ashkenazi populations and they present figures for the Romani population for the first time. Both mutations may be significant causative factors among the NSRD cases of the respective populations in Central Europe.

Mutation history of the roma/gypsies

The 8-10 million European Roma/Gypsies are a founder population of common origins that has subsequently split into multiple socially divergent and geographically dispersed Gypsy groups. Unlike other founder populations, whose genealogy has been extensively documented, the demographic history of the Gypsies is not fully understood and, given the lack of written records, has to be inferred from current genetic data. In this study, we have used five disease loci harboring private Gypsy mutations to examine some missing historical parameters and current structure. We analyzed the frequency distribution of the five mutations in 832-1,363 unrelated controls, representing 14 Gypsy populations, and the diversification of chromosomal haplotypes in 501 members of affected families. Sharing of mutations and high carrier rates supported a strong founder effect, and the identity of the congenital myasthenia 1267delG mutation in Gypsy and Indian/Pakistani chromosomes provided the best evidence yet of the Indian origins of the Gypsies. However, dramatic differences in mutation frequencies and haplotype divergence and very limited haplotype sharing pointed to strong internal differentiation and characterized the Gypsies as a founder population comprising multiple subisolates. Using disease haplotype coalescence times at the different loci, we estimated that the entire Gypsy population was founded approximately 32-40 generations ago, with secondary and tertiary founder events occurring approximately 16-25 generations ago. The existence of multiple subisolates, with endogamy maintained to the present day, suggests a general approach to complex disorders in which initial gene mapping could be performed in large families from a single Gypsy group, whereas fine mapping would rely on the informed sampling of the divergent subisolates and searching for the shared genomic region that displays the strongest linkage disequilibrium with the disease.

Hereditary and acquired angioedema: problems and progress: proceedings of the third C1 esterase inhibitor deficiency workshop and beyond

Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

Mutation screening of the C1 inhibitor gene among Hungarian patients with hereditary angioedema

Hereditary angioneurotic edema (HAE) is an autosomal dominant disorder characterized by episodic local subcutaneous and submucosal edema caused by the deficiency of activated C1 esterase inhibitor protein (C1-INH, type I (C1NH): reduced serum antigen level, type II: reduced activity and normal serum antigen level). The aim of the present study was to determine the disease-causing mutations in the C1INH gene (SERPING1) among Hungarian HAE-patients. The estimated number of affected HAE-families in Hungary is 40-50, out of which 26 families (type I:23, type II:3) managed in a single center were enrolled in the current study. To detect large deletions/insertions, we used Southern-blotting analysis followed by real time PCR based gene dosage analysis. In the absence of large structural changes, we employed direct sequencing covering the whole coding region and splicing sites of the C1INH gene. Large deletions were detected in 4/23 (17.4%) type I families. We found the g.16788C>T (p.Arg444Cys) mutation in each 3, type II HAE-families. In the remaining type I families, 13 previously unreported mutations (g.638G>A, g.2238C>T, g.2534_2535delCT, g.2579_2620del42, g.2533G>A, g.2695G>A, g.2696_2697insT, g.4467C>T, g.14224A>T, g.14107delA, g.16749_;16775dup, g.16810T>A, g.16885C>G) were detected in 16 families affecting primarily exon 3 (6/13) of the C1INH gene. In the 3 remaining families, known mutations were identified affecting primarily exon 8 (2/3).

Genotype Screening for Hereditary Hemochromatosis among Voluntary Blood Donors in Hungary

Hereditary hemochromatosis (HH) is a common genetic disorder. Although it is inherited in an autosomal recessive manner, heterozygous individuals are believed to be protected against iron deficiency. Screening to estimate the prevalence of HH was frequently performed among blood donors, not considering that carriers of the HH gene mutations may be present in higher proportion in this population. To examine the allele frequencies of the HH gene (HFE) point mutations, C282Y and H63D genotyping was carried out in 996 consecutive, first-time, and regular Hungarian blood donors by PCR-RFLP techniques. Iron parameters of the first-time donors and the identified C282Y heterozygotes and age, gender, and number of previous blood donation-matched wild-type donors were also determined. We were not able to demonstrate a significant increase in the frequency of C282Y and H63D alleles among regular blood donors, compared to first-time blood donors. However, there was a trend of higher C282Y allele frequency among women with higher number of previous blood donations (2.2 +/- 1.5% in female blood donors with 0-8 previous blood donations compared to 4.8 +/- 2.3% in women with more than 8 previous blood donations, P = 0.06). No detectable phenotypic differences were observed in serum iron, ferritin, and transferrin saturation values between C282Y wild-type and heterozygous groups. However, the single identified C282Y homozygous male (age 21) showed definite signs of iron overload. Our observations suggest that the protective effect of C282Y heterozygosity against iron deficiency may be less significant than other environmental (e.g., iron-rich diet) or genetic factors.

[A new method of molecular testing in the differential diagnosis of hereditary hemochromatosis]

Hereditary hemochromatosis is an autosomal, recessive disorder of the iron metabolism. The hemochromatosis gene (HFE) was previously located on chromosome 6 and recently identified by positional cloning. A point mutation, C282Y, was found to be present in the HFE gene in homozygous form in 64 to 100% of patients with established hemochromatosis. The relationship of a second polymorphic variant of the HFE gene, H63D to the formation of iron overload is debated. Although hemochromatosis is one of the most common inherited disorders among Caucasians, in the absence of specific signs it is rarely diagnosed. In order to obtain comparable epidemiological data for Hungary, we tested 1271 and 277 randomly selected, unrelated, healthy subjects for C282Y and H63D respectively. In addition C282Y testing was carried out in 58 patients suffering from liver cirrhosis, and in 191 individuals with suspected hemochromatosis. For C282Y and H63D mutation analyses polymerase chain reaction technique followed by Rsa I and Bcl I restriction enzyme digestion was used. We developed an alternative method for the detection of C282Y based on an amplification-generated Kpn I restriction site. The allele frequencies were 3.8% and 12.3% for C282Y and H63D respectively in the normal Hungarian population. There was no significant difference in C282Y allele frequencies between liver disease patients (1.7%) and the normal population. We identified 15 homozygous and 25 heterozygous individuals among 191 individuals with suspected hemochromatosis. The C282Y and the H63D allele frequencies in the normal Hungarian population were found to be similar to the allele frequencies observed in other European populations, indicating that there is a large number of individuals susceptible for iron overload in Hungary (1:700). Mutation analysis is a novel, non-invasive method in the diagnostics of hereditary hemochromatosis, which increasingly becomes part of the routine clinical work.

[Detection of human papillomavirus infection by the nucleic acid hybridization method (a multicenter study)]

The human papillomaviruses (HPV) are regarded as one of the important agents of cervical carcinoma. A multicentre study was organized to determine the prevalence of HPV in the fertile female population in Hungary. Parallel with the clinical sample collection, a questionnaire interview was performed to acquire data on the life style, socioeconomic status, sexual practice, etc. 1200 women were examined colposcopically and cervix samples were collected for cytology and the detection of HPV DNA. 17.4% of the samples were HPV-infected. 3.9% of the patients had acquired low-risk, and 10.1% 10.2% high-risk HPV types; 3.4% of the women were at the same time infected with both low-risk and high-risk HPV types. Simultaneously performance of cytology and the HPV hybrid capture assay contribute to recognise and treat the precancerous status and risk factors.

High frequency of the haemochromatosis C282Y mutation in Hungary could argue against a Celtic origin of the mutation

Images

Synthetic peptides comprising defined sequences of CH-2 and CH-3 domains of human IgG1 induce prostaglandin E2 production from human peripheral blood mononuclear cells

Synthetic peptides Y48 and Y75 comprising sequences at exposed sites within the CH-2 and CH-3 domains of human IgG1 at a concentration of 10(-5) M, increase PGE2 production by human peripheral blood mononuclear cell (PBMC) cultures. An increase of leukocyte migration inhibitory factor (LMIF) production in PBMC cultures--as a result of synthetic peptide treatment--was also observed. This LMIF activity, to some extent, is attributed to the PGE2 production by the cells; the inhibition of leukocyte migration being abolished by the presence of indomethacine or antibody to PGE2.

Silibinin (Legalon-70) enhances the motility of human neutrophils immobilized by formyl-tripeptide, calcium ionophore, lymphokine and by normal human serum

Experiments reported here were designed to investigate the effect of silibinin (extracted from Silybum marianum) on human polymorphonuclear leukocyte (PMN) motility and on leukocyte immobilizing activity of lymphokine (leukocyte inhibitory factor, LIF), formyl-Met-Leu-Phe (fMLP), calcium ionophore A-23187 and human sera inactivated by heat (HI-S). In the in vitro experiments, silibinin (1-10 micrograms/ml) failed to influence the random motility of unstimulated PMNS in agarose droplet assay, but enhanced the motility of the PMNs immobilized by fMLP, calcium ionophore, LIF or by autologous human sera. In the in vivo study, silibinin (Legalon-70) two hours after the administration was effective in enhancing spontaneous motility of leukocytes obtained from health volunteers which action could be regarded as a consequence of the decrease of leukocyte immobilizing activity being present in normal human plasma.

Ketoconazole in vitro inhibits mitogen-induced blastogenesis, antibody-dependent cellular cytotoxicity, natural killer activity and random migration of human leukocytes

Ketoconazole at concentrations of 1-10 micrograms/ml dose dependently inhibits mitogen-induced blastogenesis, antibody-dependent and spontaneous cytotoxic (natural killer) activity of human lymphocytes and random migration of human leukocytes. Lectin-dependent cytotoxic activity is not affected by the drug.

Effect of prostaglandins on polymorphonuclear leukocyte motility

The effect of prostaglandins (PGE1, E2, F2 alpha on LIF production, LIF activity, and on the random migration of polymorphonuclear leukocytes was investigated. Concanavalin A-induced LIF production was tested in an indirect LIF assay using agarose microdroplet technique; PGE1 and PGE2 inhibited the LIF production. PGE1, PGE2, and F2 alpha in physiological concentration, decreased the random migration of leukocytes, they also interfered with the LIF activity of supernatants, decreasing their inhibitory effect on cell migration; but the opposite explanation that LIF-treated PMNs escaped the inhibitory effect of PGs, cannot be ruled out. Macrophages produce supernatant factor(s) in the course of phagocytosis which inhibit the motility of polymorphonuclear leukocytes. The active component of supernatant seems to be PG, since its production can be blocked by indomethacin. These data indicate that prostaglandins may have different sites of attack in the local regulation of leukocyte motility.

Sensitivity of preincubated lymphocytes to suppressor regulation

DNA synthesis of human peripheral blood lymphocytes increases if Con A is added to the culture after 24 h preincubation at 37 degrees C. During preincubation the mitogen reactive lymphocytes lose their sensitivity to the suppressive effect of autologous mitomycin-treated mononuclear leukocytes, and of supernatants of autologous preincubated cells. The reactive lymphocytes preincubated at 4 degrees C retain their sensitivity to the suppressive effect of regulatory cells and their supernatants. It is assumed that the enhancement of mitogen response after preincubation at 37 degrees C is caused by a decrease of suppressor regulation of human lymphocytes. Prostaglandins may be regarded as one of the mediators of the suppression.

One-step indirect migration inhibiton (LIF) assay

A simple, 1-step indirect leukocyte migration inhibition (LIF) assay is described. Advantages of this method are as follows: the mitogen does not directly influence the migration of polymorphonuclear leukocytes, relatively few cells are needed, and results are obtained within 24 h. LIF is simultaneously produced by Con A-pretreated lymphocytes in the migration test system. The lymphokine-producing cells are in the test plate well, in the culture medium surrounding the agarose droplets containing migrating cells. The LIF production can be inhibited by the protein synthesis inhibitor puromycin and by prostaglandin (PGE1). In this test system the LIF production is not influenced by endogenous prostaglandins. This method can be used for complex immunopharmacological investigations because effects of agents on the random migration of polymorphonuclear leukocytes and on LIF production of lymphocytes can be tested in the same system.

Enhancement of mitogen-induced lymphocyte proliferation after preincubation is due to altered sensitivity to prostaglandins

Twenty-four hour preincubation at 37 degrees enhances the mitogen-induced DNA synthesis of human lymphocytes. PGE1, given simultaneously with Con A at the start of lymphocyte culture, inhibits the DNA synthesis. After 24 h preincubation of cells, PGE1 fails to decrease the DNA synthesis. Similarly, preincubation abolished the effect of indomethacin increasing DNA synthesis of freshly separated lymphocytes. The intracellular cAMP level of human mononuclear leukocytes rapidly decreases during in vitro incubation at 37 degrees C. PGE1 elevates the intracellular cAMP of freshly separated lymphocytes to 45 times of its starting level. After 24 h preincubation of cells at 37 degrees C, PGE1 elevates cAMP to a lesser extent. This change of PGE1 action may explain the fact that the effect of exogenous PGE1 and endogenous prostaglandins (the production of which can be inhibited by indomethacin) diminishes after incubation of lymphocytes. It is very likely that the change of the effect of prostaglandins produced in lymphocyte cultures and the spontaneous decrease of intracellular cAMP level explains the enhancement of mitogen-induced lymphocyte proliferation after 24 h preincubation at 37 degrees C.

Effect of treatment with glutaurine on human antibody-dependent cell-mediated cytotoxicity (ADCC)

The effects of in vitro and in vivo treatment with glutaurine, a newly discovered parathyroid hormone possessing immunostimulative activity, on human antibody-dependent cell-mediated cytotoxicity (ADCC) were studied in 15 tumor patients with healthy subjects in a xenogeneic test system using chicken erythrocytes as target cells. A marked increase in "K" cell activity was observed in 8 tumor patients with originally low cytotoxic capacity, while originally normal ADCC activity of other tumor patients and healthy subjects was not significantly influenced by glutaurine treatment. The changes in cytotoxicity were not accompanied by changes in lymphocyte populations. Incubation of effector cells with glutaurine in vitro caused no change in ADCC activity in lymphocyte populations. Some similarities between the effects of glutaurine treatment of ADCC and that of dialyzable leukocyte extracts are discussed.

Chromosome mutations and chromosome stability in children treated with different regimes of immunosuppressive drugs

The chromosome mutations and the number of sister chromatid exchanges induced by different kinds of immunosuppressive treatment were investigated in children and adults with certain types of renal diseases. The aim of the study was to find among the treatment schedules those promising good therapeutic results with the least mutagenic effects. A slightly decreased chromosome stability was found in the patients treated by cyclophosphamide therapy.

In vitro effect of transfer factor on active rosettes and leucocyte migration of patients with cancer

The in vitro effect of transfer factor (TF) and its obtained by gel filtration was studied on the active rosettes and leucocyte migration inhibition. TF and one fraction (IV) restored the reactivity of lymphocytes from tumour-bearing patients to tuberculin and Candida antigens in the leucocyte migration assay. TF and fraction IV was also found to enhance the number of active rosettes of tumour-bearing patients, whereas no such effect was observed on lymphocytes of patients with active SLE or controls.