Differential effects of nitric oxide deficiency on primary tumour growth, pulmonary metastasis and prostacyclin/thromboxane A2 balance in orthotopic and intravenous murine models of 4T1 breast cancer

The role of nitric oxide (NO) in tumour progression and metastasis is not clear, therefore the present work aimed to better characterise the effects of nitric oxide synthase (NOS) inhibition by L-N^ω-nitroarginine methyl ester (L-NAME) on primary tumour growth, pulmonary metastasis, inflammatory state and prostacyclin (PGI₂)/thromboxane A₂ (TXA₂) balance in a 4T1 murine model of breast cancer. To distinguish effects of NO deficiency on disease development, 4T1 cancer cells were administered orthotopically or intravenously to Balb/c mice. The systemic NO bioavailability, pulmonary inflammation and plasma levels of thromboxane B₂ (TXB₂) and 6-keto-prostaglandin F_1α (6-keto-PGF_1α) were assessed. The study shows that, in the orthotopic model of 4T1 breast cancer, L-NAME hampered primary tumour growth, reduced pulmonary metastases, delayed inflammatory response but did not alter biosynthesis of TXB₂ and 6-keto-PGF_1α as well as PGI₂/TXA₂ ratio in cancer-bearing mice. Interestingly, in the intravenous model of 4T1 breast cancer, NOS inhibition did not influence metastasis nor inflammation, but it increased both TXB₂ and 6-keto-PGF_1α biosynthesis without affecting PGI₂/TXA₂ ratio. In conclusion, in a 4T1 murine model of metastatic breast cancer, NO plays a major role in primary tumour development, while NO is not the key mediator of cancer cell extravasation to the lungs. Furthermore, NO-deficiency activates a PGI₂-dependent compensatory mechanism only in the intravenous model of 4T1 breast cancer.

Chronic stress changes prepulse inhibition after amphetamine challenge: the role of the dopaminergic system

The goal of this research was to examine the influence of chronic mild stress (CMS) on prepulse inhibition (PPI). We used an amphetamine challenge to study the role of the dopaminergic system in limbic structures. Chronic stress caused a reduction in both sucrose preference and body weight. It was found that the initially strong response to amphetamine in the control rats was weakened after stress on both the behavioural and biochemical levels: improved PPI, decreased dopamine D2 receptor expression in the central nucleus of amygdala (CeA) and nucleus accumbens (NAC), and decreased dopamine and 3-MT (3-methoxytyramine) levels in NAC. We observed that the stress-evoked attenuation of amphetamine-induced stimulation was also paralleled by changes in corticosterone level. These effects were accompanied by a decrease in both glutamate and the glutamate/gamma-aminobutric acid (GABA) ratio in the NAC. The interpretation of these results is that prolonged stress induces compensatory mechanisms in the mesolimbic system which are responsible for psychostimulant (amphetamine) effects.

Influence of Renin-Angiotensin System Blockers on Graft Function in Retrospective Analysis of Pairs of Renal Transplant Recipients From the Same Donor

BACKGROUND

Renin-angiotensin system (RAS) blocking agents efficiently control hypertension in renal transplant recipients (RTRs), and reduce proteinuria and post-transplant erythrocytosis. A beneficial effect on the retardation of the long-term decline in renal function has not yet been demonstrated. The aim of the study was to evaluate the effects of RAS blockade on allograft function.

METHODS

In order to minimize donor variability and bias, 33 pairs of RTRs receiving grafts from the same donor were included into the retrospective analysis. A total of 66 RTRs were enrolled in which 1 patient from the pair used an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker for a minimum period of 60 months (RAS[+]) and the second one did not use it at all (RAS[-]).

RESULTS

There were no differences between RAS(+) and RAS(-) subjects in terms of age, body mass index, mismatches number, duration of total ischemia, episodes of cytomegalovirus infections, acute rejections, or immunosuppressive treatment. Significantly, more RAS(+) patients presented with diabetes and cardiovascular complications. Among RAS(+) patients, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers were used in 28 (84.84%) and 5 (15.15%) patients in a mean dose of 23.03 ± 16.83% and 30 ± 11.18% of their maximum doses, respectively. There were no significant differences in estimated glomerular filtration rate changes (-0.37 ± 12.68 vs 2.54 ± 20.76 mL/min) and serum creatinine changes (0.05 ± 0.39 vs 0.14 ± 0.79 mg/dL) between RAS(+) and RAS(-) patients during the 60 months follow-up.

CONCLUSION

Agents inhibiting the RAS did not significantly affect graft function in RTRs during 60 months of observation.

Cardiovascular and Renal Outcomes of Renin-Angiotensin System Blockade in Renal Transplant Recipients

BACKGROUND

There is considerable controversy over the benefits of renin-angiotensin system (RAS) blockade in renal transplant recipients (RTRs). The aim of the study was to research the effects of RAS blockade on allograft and patient outcome.

METHODS

A retrospective analysis of the effects of RAS blockade on allograft and patient outcome in 53 pairs of RTRs receiving grafts from the same donor was performed. The 106 RTRs (53 pairs), transplanted from 2002 to 2012, were included in the study when 1 patient from the pair used an angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) for a minimum period of 36 months (RAS[+]) and the second one did not use it (RAS[-]).

RESULTS

There were no differences between RAS(+) and RAS(-) subjects in terms of age, body mass index, reason of end-stage renal disease, mismatches number, total ischemic time, episodes of cytomegalovirus infections, acute rejections, and immunosuppressive treatment. The mean time of observations was 66.28 months ± 24.39 months. RAS inhibitors were given in a mean dose of 23.1% (ACEI) and 27.08% (ARB) of the maximum recommended. The main reasons for the therapy were as follows: hypertension (39.62%), nephroprotection/proteinuria (39.62%), and polyglobulia (28.3%). The composite cardiorenal endpoint was reached by 6 (11.32%) and 7 (13.21%) patients in RAS(+) and RAS(-) group, respectively. There were no differences in changes of creatinine, potassium serum level, or estimated glomerular filtration rate between RAS(+) and RAS(-) patients in the early period after RAS blockade commencement.

CONCLUSION

Agents inhibiting the RAS system neither improved nor deteriorated patients and graft survival in RTRs.

Real-Time qPCR as a Method for Detection of Antibody-Neutralized Phage Particles

The most common method for phage quantitation is the plaque assay, which relies on phage ability to infect bacteria. However, non-infective phage particles may preserve other biological properties; specifically, they may enter interactions with the immune system of animals and humans. Here, we demonstrate real-time quantitative polymerase chain reaction (qPCR) detection of bacteriophages as an alternative to the plaque assay. The closely related staphylococcal bacteriophages A3R and 676Z and the coliphage T4 were used as model phages. They were tested in vivo in mice, ex vivo in human sera, and on plastic surfaces designed for ELISAs. T4 phage was injected intravenously into pre-immunized mice. The phage was completely neutralized by specific antibodies within 5 h (0 pfu/ml of serum, as determined by the plaque assay), but it was still detected by qPCR in the amount of approximately 10⁷ pfu/ml of serum. This demonstrates a substantial timelapse between "microbiological disappearance" and true clearance of phage particles from the circulation. In human sera ex vivo, qPCR was also able to detect neutralized phage particles that were not detected by the standard plaque assay. The investigated bacteriophages differed considerably in their ability to immobilize on plastic surfaces: this difference was greater than one order of magnitude, as shown by qPCR of phage recovered from plastic plates. The ELISA did not detect differences in phage binding to plates. Major limitations of qPCR are possible inhibitors of the PCR reaction or free phage DNA, which need to be considered in procedures of phage sample preparation for qPCR testing. We propose that phage pharmacokinetic and pharmacodynamic studies should not rely merely on detection of antibacterial activity of a phage. Real-time qPCR can be an alternative for phage detection, especially in immunological studies of bacteriophages. It can also be useful for studies of phage-based drug nanocarriers or biosensors.

Effects of a single bout of strenuous exercise on platelet activation in female ApoE/LDLR-/- mice

Strenuous physical exercise leads to platelet activation that is normally counterbalanced by the production of endothelium-derived anti-platelet mediators, including prostacyclin (PGI₂) and nitric oxide (NO). However, in the case of endothelial dysfunction, e.g. in atherosclerosis, there exists an increased risk for intravascular thrombosis during exercise that might be due to an impairment in endothelial anti-platelet mechanisms. In the present work, we evaluated platelet activation at rest and following a single bout of strenuous treadmill exercise in female ApoE/LDLR^-/- mice with early (3-month-old) and advanced (7-month-old) atherosclerosis compared to female age-matched WT mice. In sedentary and post-exercise groups of animals, we analyzed TXB₂ generation and the expression of platelet activation markers in the whole blood ex vivo assay. We also measured pre- and post-exercise plasma concentration of 6-keto-PGF_1α, nitrite/nitrate, lipid profile, and blood cell count. Sedentary 3- and 7-month-old ApoE/LDLR^-/- mice displayed significantly higher activation of platelets compared to age-matched wild-type (WT) mice, as evidenced by increased TXB₂ production, expression of P-selectin, and activation of GPIIb/IIIa receptors, as well as increased fibrinogen and von Willebrand factor (vWf) binding. Interestingly, in ApoE/LDLR^-/- but not in WT mice, strenuous exercise partially inhibited TXB₂ production, the expression of activated GPIIb/IIIa receptors, and fibrinogen binding, with no effect on the P-selectin expression and vWf binding. Post-exercise down-regulation of the activated GPIIb/IIIa receptor expression and fibrinogen binding was not significantly different between 3- and 7-month-old ApoE/LDLR^-/- mice; however, only 7-month-old ApoE/LDLR^-/- mice showed lower TXB₂ production after exercise. In female 4-6-month-old ApoE/LDLR^-/- but not in WT mice, an elevated pre- and post-exercise plasma concentration of 6-keto-PGF_1α was observed. In turn, the pre- and post-exercise plasma concentrations of nitrite (NO₂^-) and nitrate (NO₃^-) were decreased in ApoE/LDLR^-/- as compared to that in age-matched WT mice. In conclusion, we demonstrated overactivation of platelets in ApoE/LDLR^-/- as compared to WT mice. However, platelet activation in ApoE/LDLR^-/- mice was not further increased by strenuous exercise, but was instead attenuated, a phenomenon not observed in WT mice. This phenomenon could be linked to compensatory up-regulation of PGI₂-dependent anti-platelet mechanisms in ApoE/LDLR^-/- mice.

The N-end rule proteolytic system in autophagy

The N-end rule pathway is a cellular proteolytic system that utilizes specific N-terminal residues as degradation determinants, called N-degrons. N-degrons are recognized and bound by specific recognition components (N-recognins) that mediate polyubiquitination of low-abundance regulators and selective proteolysis through the proteasome. Our earlier work identified UBR4/p600 as one of the N-recognins that promotes N-degron-dependent proteasomal degradation. In this study, we show that UBR4 is associated with cellular cargoes destined to autophagic vacuoles and is degraded by the lysosome. UBR4 loss causes multiple misregulations in autophagic pathways, including an increased formation of LC3 puncta. UBR4-deficient mice die during embryogenesis primarily due to defective vascular development in the yolk sac (YS), wherein UBR4 is associated with a bulk lysosomal degradation system that absorbs maternal proteins from the YS cavity and digests them into amino acids. Our results suggest that UBR4 plays a role not only in selective proteolysis of short-lived regulators through the proteasome, but also bulk degradation through the lysosome. Here, we discuss a possible mechanism of UBR4 as a regulatory component in the delivery of cargoes destined to interact with the autophagic core machinery.

Molecular characteristics of cancer stem-like cells derived from human breast cancer cells

We characterized the cellular properties of cancer stem-like cells (CSLCs) isolated from immortalized MDA-MB453 human breast cancer cells in culture. We showed that although the expression of Octamer-binding transcription factor-4 (OCT4) correlates to stemness in these CSLCs, OCT4 knockdown does not induce their differentiation. Our results suggest that the differentiation program in MDA-MB453 CSLCs is blocked at a step upstream of the transcription of the OCT4 promoter, allowing CSLCs to maintain their population through asymmetric cell division during many repeated passages. Comparative expression analysis indicates that only a subset of genes and signaling pathways known to be associated with survival and maintenance of CSCs are selectively expressed in CSLCs, as compared with non-CSLCs fractionated from the same parental MDA-MB453 cells. These results suggest that selective expression of a limited number of genes may be sufficient for establishment and maintenance of CSLCs with high tumorigenicity.

Characterization of arginylation branch of N-end rule pathway in G-protein-mediated proliferation and signaling of cardiomyocytes

The N-end rule pathway is a proteolytic system in which destabilizing N-terminal amino acids of short lived proteins are recognized by recognition components (N-recognins) as an essential element of degrons, called N-degrons. In eukaryotes, the major way to generate N-degrons is through arginylation by ATE1 arginyl-tRNA-protein transferases, which transfer Arg from aminoacyl-tRNA to N-terminal Asp and Glu (and Cys as well in mammals). We have shown previously that ATE1-deficient mice die during embryogenesis with defects in cardiac and vascular development. Here, we characterized the arginylation-dependent N-end rule pathway in cardiomyocytes. Our results suggest that the cardiac and vascular defects in ATE1-deficient embryos are independent from each other and cell-autonomous. ATE1-deficient myocardium and cardiomyocytes therein, but not non-cardiomyocytes, showed reduced DNA synthesis and mitotic activity ~24 h before the onset of cardiac and vascular defects at embryonic day 12.5 associated with the impairment in the phospholipase C/PKC-MEK1-ERK axis of Gα(q)-mediated cardiac signaling pathways. Cardiac overexpression of Gα(q) rescued ATE1-deficient embryos from thin myocardium and ventricular septal defect but not from vascular defects, genetically dissecting vascular defects from cardiac defects. The misregulation in cardiovascular signaling can be attributed in part to the failure in hypoxia-sensitive degradation of RGS4, a GTPase-activating protein for Gα(q). This study is the first to characterize the N-end rule pathway in cardiomyocytes and reveals the role of its arginylation branch in Gα(q)-mediated signaling of cardiomyocytes in part through N-degron-based, oxygen-sensitive proteolysis of G-protein regulators.

The substrate recognition domains of the N-end rule pathway

The N-end rule pathway is a ubiquitin-dependent system where E3 ligases called N-recognins, including UBR1 and UBR2, recognize type-1 (basic) and type-2 (bulky hydrophobic) N-terminal residues as part of N-degrons. We have recently reported an E3 family (termed UBR1 through UBR7) characterized by the 70-residue UBR box, among which UBR1, UBR2, UBR4, and UBR5 were captured during affinity-based proteomics with synthetic degrons. Here we characterized substrate binding specificity and recognition domains of UBR proteins. Pull-down assays with recombinant UBR proteins suggest that 570-kDa UBR4 and 300-kDa UBR5 bind N-degron, whereas UBR3, UBR6, and UBR7 do not. Binding assays with 24 UBR1 deletion mutants and 31 site-directed UBR1 mutations narrow down the degron-binding activity to a 72-residue UBR box-only fragment that recognizes type-1 but not type-2 residues. A surface plasmon resonance assay shows that the UBR box binds to the type-1 substrate Arg-peptide with Kd of approximately 3.4 microm. Downstream from the UBR box, we identify a second substrate recognition domain, termed the N-domain, required for type-2 substrate recognition. The approximately 80-residue N-domain shows structural and functional similarity to 106-residue Escherichia coli ClpS, a bacterial N-recognin. We propose a model where the 70-residue UBR box functions as a common structural element essential for binding to all known destabilizing N-terminal residues, whereas specific residues localized in the UBR box (for type 1) or the N-domain (for type 2) provide substrate selectivity through interaction with the side group of an N-terminal amino acid. Our work provides new insights into substrate recognition in the N-end rule pathway.

Hypoxia-activated metabolic pathway stimulates phosphorylation of p300 and CBP in oxygen-sensitive cells

Transcription co-activators and histone acetyltransferases, p300 and cyclic AMP responsive element-binding protein-binding protein (CBP), participate in hypoxic activation of hypoxia-inducible genes. Here, we show that exposure of PC12 and cells to 1-10% oxygen results in hyperphosphorylation of p300/CBP. This response is fast, long lasting and specific for hypoxia, but not for hypoxia-mimicking agents such as desferioxamine or Co2+ ions. It is also cell-type specific and occurs in pheochromocytoma PC12 cells and the carotid body of rats but not in hepatoblastoma cells. The p300 hyperphosphorylation specifically depends on the release of intracellular calcium from inositol 1,4,5-triphosphate (IP3)-sensitive stores. However, it is not inhibited by pharmacological inhibitors of any of the kinases traditionally known to be directly or indirectly calcium regulated. On the other hand, p300 hyperphosphorylation is inhibited by several different inhibitors of the glucose metabolic pathway from generation of NADH by glyceraldehyde 3-phosphate dehydrogenase, through the transfer of NADH through the glycerol phosphate shuttle to ubiquinone and complex III of the mitochondrial respiratory chain. Inhibition of IP3-sensitive calcium stores decreases generation of ATP, and this inhibition is significantly stronger in hypoxia than in normoxia. We propose that the NADH glycerol phosphate shuttle participates in generating a pool of ATP that serves either as a co-factor or a modulator of the kinases involved in the phosphorylation of p300/CBP during hypoxia.

Complementation of yeast Arc1p by the p43 component of the human multisynthetase complex does not require its association with yeast MetRS and GluRS

Yeast Arc1p, human p43 and plant methionyl-tRNA synthetase (MetRS) possess an EMAPII-like domain capable of non-specific interactions with tRNA. Arc1p interacts with MetRS (MES1) and GluRS and operates as a tRNA-interacting factor (tIF) in trans of these two synthetases. In plant MetRS, the EMAPII-like domain is fused to the catalytic core of the synthetase and acts as a cis-acting tIF for aminoacylation. We observed that the catalytic core of plant MetRS expressed from a centromeric plasmid cannot complement a yeast arc1(-) mes1(-) strain. Overexpression of the mutant enzyme from a high-copy number plasmid restored cell growth, suggesting that deletion of its C-terminal tIF domain was responsible for the poor aminoacylation efficiency of that enzyme in vivo. Accordingly, expression of full-size plant MetRS from a centromeric plasmid, but also of fusion proteins between its catalytic core and the EMAPII-like domains of yeast Arc1p or of human p43 restored cell viability. These data showed that homologous tIF domains from different origins are interchangeable and may act indifferently in trans or in cis of the catalytic domain of a synthetase. Unexpectedly, co-expression of Arc1p with the catalytic core of plant MetRS restored cell viability as well, even though Arc1p did not associate with plant MetRS. Because Arc1p also interacts with yeast GluRS, restoration of cell growth could be due at least in part to its role of cofactor for that enzyme. However, co-expression of human p43, a tIF that did not associate with plant MetRS or with yeast GluRS and MetRS, also restored cell viability of a yeast strain that expressed the catalytic core of plant MetRS. These results show that p43 and Arc1p are able to facilitate tRNA aminoacylation in vivo even if they do not interact physically with the synthetases. We propose that p43/Arc1p may be involved in sequestering tRNAs in the cytoplasm of eukaryotic cells, thereby increasing their availability for protein synthesis.

Relationship between passive smoking, recurrent respiratory tract infections and otitis media in children

The cause of upper respiratory tract infections (URTI) are multifactorial (enlarged adenoid, environmental conditions, staying at the care centers, smoking parents, allergy). Directly, viral infection causes damage to the ciliary cells and mucociliary clearance in the nasopharynx and Eustachian tube, promotes tubal occlusion and provokes otitis media. Enlarged adenoids reduce ventilation to the nasopharynx, increase accumulation of the secretion and provide a good condition for bacteria.

AIMS OF THE STUDY

Evaluation of the factors playing a role in recurrent URTI and otitis media in children. Clinical and histopathological examination of adenoid tissue of children who were passive smokers and children who were not exposed to cigarette smoke. Evaluation of the difference between ciliary-mucous transport among passive smokers and children not exposed to cigarette smoke.

METHODS

The analysis of interview questionnaires in 1000 children aged 3-14 years. Histopathological examinations of adenoid tissue excised in the group of children of recurrent upper respiratory tract infections and serous otitis media exposed and not exposed to cigarette smoke.

CONCLUSIONS

Among the risk factors for URTI, the most important are: (1) socio-economic conditions; (2) staying at day care centers; and (3) passive smoking. Allergy was confirmed in 35-38% of URTI children. Surgical treatment was undertaken in 11.4-32.5% of URTI children (tonsilloadenoidectomy). Histopathological and ultrastructural evaluation of adenoid tissue in passive smoking children indicates significant differences to children not exposed to cigarette smoke.

Evaluation of the effectiveness of vaccination against diphtheria among medical staff of the chair and the Jagiellonian University Hospital of Infectious Diseases in Cracow, Poland. Some epidemiological observations

In Poland, twenty-five cases of diphtheria, mostly among adults (including five foreigners) in the region adjacent to the eastern border were registered in the years 1992-1996. In 1993-1994, because of the threat of diphtheria infection, 41 healthy members of the medical staff of the University Hospital of Infectious Diseases in Kraków, mainly women aged 25-57 years were immunized with Td and d vaccines with a 6-month interval between courses. Prior to vaccination, 17(41%) individuals showed a lack of diphtheria antibodies as determined with a passive haemagglutination test. 14 of them were aged 30-49 years. Six months after the 2nd dose of vaccine, all seronegative persons had developed a protective level of antibodies. Moreover, all vaccinated subjects showed a statistically significant increase of the antibody titre between the first and last serological examinations.

[Diphtheria and tetanus immunity of blood donors]

Immunity to diphtheria and tetanus was determined in serum samples from 108 blood donors. Antitoxin concentration was evaluated by ELISA assay. 65% of donors were protected to diptheria and 100% to tetanus. Significant trend of decreasing immunity was observed with increasing age.

Changes in age specific immunity to diphtheria in Poland in the past 40 years

In recent years people in Poland have acquired diphtheria from eastern neighbours. It was considered important therefore to study the age specific immunity against diphtheria and to compare it with the results of seroepidemiological studies conducted in t

[The immunochemical characteristics of adult sera after Td vaccination]

The results of immunochemical test of 29 adults sera before and after Td vaccination were presented. The level of 12 protein fractions was in normal range value in 26 of examined sera. There was IgA deficiency in one serum, in two others haptoglobin deficiency and high levels of transferrin and IgM were observed.

[Usefulness of the cytotoxic test for testing levels of diphtheria antibodies in sera of immunized animals]

Vero cells method was used for determination of antibodies level in humans vaccinated with Td vaccine and also in animals immunized with Di, DiTe, Td and DTP vaccines. We have found quite high levels of antibodies in both groups of animals. There was also a significant increase of antibody level in the human sera after Td booster dose in the CCV and HA tests, but the correlation with antitoxin titre was low. CCV test could be useful for determination of immunogenicity of diphtheria toxid.

The influence of tonsillectomy on obstructive sleep apnea children with malocclusion

Adeno-tonsillar hypertrophy is the most common cause of obstructive sleep apnea syndrome (OSAS) in childhood and may also play a role in the development of craniofacial abnormalities. The mode of breathing and the morphology of the dental arch are very closely connected. Most of the children who came to the ENT clinic had malocclusions. The early performance of surgical treatment on hypertrophied tonsils and/or adenoids influenced greatly the state of health and morphology of the dental arch. In the process of diagnosis and treatment of children with OSAS it is necessary to have multidisciplinary cooperation, especially between the otolaryngologist and the orthodontist.