Natural Killer Cell Tolerance Persists Despite Significant Reduction of Self MHC Class I on Normal Target Cells in Mice

Background

A major group of murine inhibitory receptors on Natural Killer (NK) cells belong to the Ly49 receptor family and recognize MHC class I molecules. Infected or transformed target cells frequently downmodulate MHC class I molecules and can thus avoid CD8⁺ T cell attack, but may at the same time develop NK cell sensitivity, due to failure to express inhibitory ligands for Ly49 receptors. The extent of MHC class I downregulation needed on normal cells to trigger NK cell effector functions is not known.

Methodology/Principal Findings

In this study, we show that cells expressing MHC class I to levels well below half of the host level are tolerated in an in vivo assay in mice. Hemizygous expression (expression from only one allele) of MHC class I was sufficient to induce Ly49 receptor downmodulation on NK cells to a similar degree as homozygous expression, despite a strongly reduced cell surface level of MHC class I. Co-expression of weaker MHC class I ligands in the host did not have any further effect on the degree of Ly49 downmodulation. Furthermore, a single MHC class I allele could downmodulate up to three Ly49 receptors on individual NK cells. Only when NK cells simultaneously expressed several Ly49 receptors and hemizygous MHC class I levels, a putative threshold for Ly49 downmodulation was reached.

Conclusion

Collectively, our findings suggest that in interactions between NK cells and normal untransformed cells, MHC class I molecules are in most cases expressed in excess compared to what is functionally needed to ensure self tolerance and to induce maximal Ly49 downmodulation. We speculate that the reason for this is to maintain a safety margin for otherwise normal, autologous cells over a range of MHC class I expression levels, in order to ensure robustness in NK cell tolerance.     

Effects of Dietary Supplementation with Vitamin C and Vitamin E and Their Combination on Growth Performance,Some Biochemical Parameters,and Oxidative Stress Induced by Copper Toxicity in Broilers

This study investigated effects of dietary supplementation with vitamin C, vitamin E on performance, biochemical parameters, and oxidative stress induced by copper toxicity in broilers. A total of 240, 1-day-old, broilers were assigned to eight groups with three replicates of 10 chicks each. The groups were fed on the following diets: control (basal diet), vitamin C (250 mg/kg diet), vitamin E (250 mg/kg diet), vitamin C + vitamin E (250 mg/kg?+?250 mg/kg diet), and copper (300 mg/kg diet) alone or in combination with the corresponding vitamins. At the 6th week, the body weights of broilers were decreased in copper, copper + vitamin E, and copper + vitamin C + vitamin E groups compared to control. The feed conversion ratio was poor in copper group. Plasma aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase activities, iron, copper concentrations, and erythrocyte malondialdehyde were increased; plasma vitamin A and C concentrations and erythrocyte superoxide dismutase were decreased in copper group compared to control. Glutathione peroxidase, vitamin C, and iron levels were increased; aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and copper levels were decreased in copper + vitamin C group, while superoxide dismutase, glutathione peroxidase, and vitamin E concentrations were increased; aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase were decreased in copper with vitamin E group compared to copper group. The vitamin C concentrations were increased; copper, uric acid, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and malondialdehyde were decreased in copper + vitamin C + vitamin E group compared to copper group. To conclude, copper caused oxidative stress in broilers. The combination of vitamin C and vitamin E addition might alleviate the harmful effects of copper as demonstrated by decreased lipid peroxidation and hepatic enzymes.     

The Use of Novel Drugs Can Effectively Improve Response,Delay Relapse and Enhance Overall Survival in Multiple Myeloma Patients with Renal Impairment

Background

Renal impairment is a common feature in multiple myeloma and is considered a poor prognostic factor.

Aim

To determine the impact of novel drugs (i.e. bortezomib, lenalidomide and thalidomide) in the treatment of myeloma patients with renal impairment. The primary endpoint was overall survival and secondary endpoints were time to next treatment and response.

Methods

The study population included all patients diagnosed with treatment-demanding multiple myeloma January 2000 to June 2011 at 15 Swedish hospitals. Renal impairment was defined as an estimated glomerular filtration rate under 60 mL/min/1.73 m².

Result

The study population consisted of 1538 patients, of which 680 had renal impairment at diagnosis. The median overall survival in patients with renal impairment was 33 months, which was significantly shorter than 52 months in patients with normal renal function (P<0.001). Novel agents in first line improved overall survival (median 60 months) in non-high-dose treated patients with renal impairment (n = 143) as compared to those treated with conventional cytotoxic drugs (n = 411) (median 27 months) (P<0.001). In the multivariate analysis up front treatment with bortezomib was an independent factor for better overall survival in non-high-dose treated renally impaired patients. High-dose treated renally impaired patients had significantly better median overall survival than non-high-dose ones (74 versus 26 months) and novel drugs did not significantly improve survival further in these patients. Patients with renal impairment had both a shorter median time to next treatment and a lower response rate than those with normal renal function. However, novel drugs and high dose treatment lead to a significantly longer time to next treatment and the use of novel agents significantly improved the response rate of these patients.

Conclusion

High dose treatment and novel drugs, especially bortezomib, can effectively overcome the negative impact of renal impairment in patients with multiple myeloma.     

Effect of silymarin on bladder overactivity in cyclophosphamide-induced cystitis rat model

The purpose of this study was to investigate the effects of silymarin, a phytotherapeutic agent, on bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model. Female Wistar Albino rats received a single intraperitoneal injection of CYP (150 mg/kg) or saline and after 72 h, bladder function was evaluated by in vitro preparations of whole bladders and cystometry with continuous saline infusion under urethane anesthesia. Silymarin or a vehicle was orally given for 7 days in rats. CYP was injected on the 5th day of silymarin or vehicle treatment and then the animals were killed on the 8th day. CYP-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. In anesthetized rats, during continuous infusion cystometry, intercontraction interval (ICI) was significantly shorter, but bladder voiding pressure was not significantly changed in CYP-injected rats compared to control rats. In the CYP-injected group, silymarin treatment significantly decreased the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions, but failed to change carbachol-induced contraction in isolated whole bladder. Also, silymarin treatment significantly increased the ICI in comparison to the vehicle treatment. In the saline-injected group, no significant changes in the bladder function were observed between the silymarin and vehicle-treated groups. Histopathological examination showed that CYP-induced bladder inflammation tended to be lower in the silymarin+CYP-treated group. In conclusion, the oral administration of silymarin suppressed CYP-induced bladder overactivity. Silymarin may be considered as an attractive treatment for CYP-induced bladder overactivity.     

Predictors of Appropriate ICD Therapy in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy: Long Term Experience of a Tertiary Care Center

Introduction

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetically transmitted disease prone to ventricular arrhythmias. We therefore investigated the clinical, echocardiographical and electrophysiological predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients with ARVC.

Methods

A retrospective analysis was performed in 26 patients (median age of 40 years at diagnosis, 21 males and 5 females) with ARVC who underwent ICD implantation.

Results

Over a median (range) follow-up period of 10 (2.7, 37) years, appropriate ICD therapy for ventricular arrhythmias was documented in 12 (46%) out of 26 patients. In all patients with appropriate ICD therapy the ICD was originally inserted for secondary prevention. Median time from ICD implantation to ICD therapy was 9 months (range 3.6, 54 months). History of heart failure was a significant predictor of appropriate ICD therapy (p = 0.033). Left ventricular disease involvement (p = 0.059) and age at implantation (p = 0.063) were borderline significant predictors. Patients with syncope at time of diagnosis were significantly less likely to receive ICD therapy (p = 0.02). Invasive electrophysiological testing was not significantly associated with appropriate ICD therapy.

Conclusion

In our cohort of patients with ARVC, history of heart failure was a significant predictor of appropriate ICD therapy, whereas left ventricular involvement and age at time of ICD implantation were of borderline significance. These predictors should be tested in larger prospective cohorts to optimize ICD therapy in this rare cardiomyopathy.     

Characterization of three maize bacterial artificial chromosome libraries toward anchoring of the physical map to the genetic map using high-density bacterial artificial chromosome filter hybridization

Three maize (Zea mays) bacterial artificial chromosome (BAC) libraries were constructed from inbred line B73. High-density filter sets from all three libraries, made using different restriction enzymes (HindIII, EcoRI, and MboI, respectively), were evaluated with a set of complex probes including the 185-bp knob repeat, ribosomal DNA, two telomere-associated repeat sequences, four centromere repeats, the mitochondrial genome, a multifragment chloroplast DNA probe, and bacteriophage lambda. The results indicate that the libraries are of high quality with low contamination by organellar and lambda-sequences. The use of libraries from multiple enzymes increased the chance of recovering each region of the genome. Ninety maize restriction fragment-length polymorphism core markers were hybridized to filters of the HindIII library, representing 6x coverage of the genome, to initiate development of a framework for anchoring BAC contigs to the intermated B73 x Mo17 genetic map and to mark the bin boundaries on the physical map. All of the clones used as hybridization probes detected at least three BACs. Twenty-two single-copy number core markers identified an average of 7.4 +/- 3.3 positive clones, consistent with the expectation of six clones. This information is integrated into fingerprinting data generated by the Arizona Genomics Institute to assemble the BAC contigs using fingerprint contig and contributed to the process of physical map construction.     

Determination of aluminum levels in the kidney,liver, and brain of mice treated with aluminum hydroxide

In the present study, aluminum (Al) accumulation has been examined after aluminum loading in mice. The kidney, liver, and brain aluminum levels for mice that had been treated orally with aluminum hydroxide for 105 d and for the control group were determined using graphite furnace atomic absorption spectrophotometry (GFAAS) following an acid digestion. Matrix modifier consisted of 2% Triton X-100 and 2% Mg (NO₃)₂. Al loaded mice showed a significant increase in tissue aluminum levels, relative to the control group.     

Aluminum content of infant formulas used in Turkey

In the past few years, there has been an upsurge of interest in aluminum (Al) and human health. The well-recognized manifestations of systemic Al toxicity include fracturing osteomalacia, dialysis encephalopathy, and microcytic hypochromic anemia. The role of Al in causing childhood diseases is also becoming clearer, but the safe plasma level still remains to be determined in newborns, especially in premature newborns, implying that it should be kept low. Premature infants receiving iv fluid therapy show evidence of Al loading. Additionally, the infant-feeding mixtures, especially the soy-based infant formulas, tested may be a significant additional source of Al in the diet of infants with low birthweights, and in infants and in young children with impaired renal function. Careful clinical and biochemical monitoring is warranted to determine whether it will be necessary to eliminate Al contamination of both oral and parenteral preparations used in infants and children who may be at risk for Al intoxication. In this present study, the Al content of infant feeds was measured by electrothermal atomic absorption spectrophotometry, and also compared with those of breast milk, cow’s milk, milk powder, and some starches that are commonly used for preparation of infant feed in Turkey. Our results show that Al content of commercially available powdered infant formulas, most of which are imported from Europe, ranged from 1.211 to 10.925 μg/g. The mean value was higher than that of breast milk. It was also found that the Al content of cow’s milk in various containers was higher than that of breast milk. The highest Al level among cow’s milk samples was in the aluminized carton box. In the other products tested, such as milk powder, the starches contained Al at various levels. Among these, milk powder and rice flour contained a high level of Al.