Arginine transport in human erythroid cells: discrimination of CAT1 and 4F2hc/y+LAT2 roles

Since arginine metabolites, such as nitric oxide and polyamines, influence the expression of genes involved in erythroid differentiation, the transport of the cationic amino acid may play an important role in erythroid cells. However, available data only concern the presence in these cells of CAT1 transporter (system y⁺), while no information exists on the role of the heterodimeric transporters of system y⁺L (4F2hc/y⁺LAT1 and 4F2hc/y⁺LAT2) which operates transmembrane arginine fluxes cis-inhibited by neutral amino acids in the presence of sodium. Using erythroleukemia K562 cells and normal erythroid precursors, we demonstrate here that arginine transport in human erythroid cells is due to the additive contributions of a leucine-sensitive and leucine-insensitive component. In both cell types, leucine inhibition of arginine influx is much less evident in the absence of sodium, a hallmark of system y⁺L. In K562 cells, N-ethylmaleimide, a known inhibitor of CAT transporters (system y⁺), suppresses only a fraction of arginine influx corresponding to leucine-insensitive uptake. Moreover, in Xenopus oocytes coexpressing 4F2hc and y⁺LAT2, leucine exerts a marked inhibition of arginine transport, partially dependent on sodium, while no inhibition is seen in oocytes expressing CAT1. Lastly, silencing of SLC7A6, the gene for y⁺LAT2, lowers arginine transport and doubles the intracellular content of the cationic amino acid in K562 cells. We conclude that arginine transport in human erythroid cells is due to both system y⁺ (CAT1 transporter) and system y⁺L (4F2hc/y⁺LAT2 isoform), which mainly contribute, respectively, to the influx and to the efflux of the cationic amino acid.     

Polyomavirus BK DNA quantification assay to evaluate viral load in renal transplant recipients.

BACKGROUND: Several studies have disclosed a correlation between polyomavirus BK (BKV) and interstitial nephritis in renal transplant recipients and its quantification in urine and serum is therefore required to assess the role of BKV infection in nephropathy. OBJECTIVE: This paper describes a urine and serum BKV-DNA quantification protocol devised to evaluate the viral load. STUDY DESIGN: Screening of samples containing > or =10(3)/ml viral genome copies by a semi-quantitative polymerase chain reaction (PCR) assay is followed by precise quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay. Generation of the competitor construct relied on the different sizes of wild-type and competitor amplicons. RESULTS AND CONCLUSIONS: Screening by semi-quantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and -expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. The results obtained in BKV-DNA quantification in urine and serum samples from 51 renal transplant recipients (22 on treatment with tacrolimus (FK506) and 29 on cyclosporine A (Cy A)) are interesting: BKV-DNA findings (43.1%) in urine samples are in agreement with the BKV urinary shedding reported in literature (5-45%). With regard to immunosuppressive treatment, the percentage of activation of the infection (revealed by BKV-DNA detection in urine samples) in the two groups of therapy is similar (40.9% vs 44.8%). The observation that the viral load in urine is dissociated with that of serum suggests that both parameters should be investigated in evaluation of the pathogenetic role of BKV reactivation in renal transplant recipients. Moreover, our BKV-DNA quantification protocol could be used to monitor viral load in urine and serum samples from renal transplant recipients so as to detect those at risk of nephropathy and monitor their response to immunosuppression reduction therapy if it occurs.     

Extended efficacy and safety of denosumab in breast cancer patients with bone metastases not receiving prior bisphosphonate therapy

PURPOSE: Denosumab, a fully human monoclonal antibody to RANKL, suppresses bone resorption. This study evaluated the effects of denosumab in i.v. bisphosphonate (IV BP)-na?ve patients with breast cancer-related bone metastases. EXPERIMENTAL DESIGN: Eligible women (n = 255), stratified by type of antineoplastic therapy, were randomized to 1 of 5 blinded denosumab cohorts or an open-label IV BP cohort. Denosumab was administered s.c. every 4 weeks (30, 120, or 180 mg) or every 12 weeks (60 or 180 mg) through 21 weeks. Final efficacy results for up to 25 weeks are reported, including percentage change from baseline in urine N-telopeptide corrected for creatinine (uNTx/Cr) and incidence of skeletal-related events (SRE). Safety results are reported through the end of follow-up (up to 57 weeks). RESULTS: At week 13 and 25, the median percent changes in uNTx/creatinine (Cr) among patients with measurable uNTx were -73% and -75% for the pooled denosumab groups and -79% and -71% for the IV BP group. Among patients with > or =1 postbaseline measurement of uNTx at week 25, 52% (109 of 208) of denosumab-treated patients and 46% (19 of 41) of IV BP-treated patients achieved >65% uNTx/Cr reduction. On-study SREs occurred in 12% (26 of 211) of denosumab-treated patients and 16% (7 of 43) of IV BP-treated patients. Overall rates of adverse events were 95% in denosumab and IV BP groups. No denosumab-related serious or fatal adverse events occurred. CONCLUSIONS: In IV BP-na?ve breast cancer patients with bone metastases, denosumab suppresses bone turnover and seems to reduce SRE risk similarly to IV BPs, with a safety profile consistent with an advanced cancer population receiving systemic therapy.     

Evaluation of the effects of anti-thromboxane agents in platelet-vessel wall interaction

We evaluated the capacity of anti-aggregating agents to influence thromboxane A(2) and prostacyclin formation, arachidonic acid-endoperoxide redirection, platelet aggregation and vessel tone, in isolated rabbit aorta incubated with homologous platelets. Picotamide (N,N'bis(3-pyridinylmethyl)-4-methoxy-isophthalamide), the only dual thromboxane A(2)-synthase inhibitor/receptor antagonist in clinical use, inhibited arachidonic acid-induced platelet aggregation with low potency, increased 180-fold by aorta presence. It inhibited thromboxane A(2) formation in platelets and, in aorta presence, increased prostacyclin formation. Ozagrel (OKY-046, (E)-3-(4-(1-imidazolylmethyl)phenyl)-2-propenoic acid), a pure thromboxane A(2)-synthase inhibitor, behaved similarly to picotamide, although the aorta caused a higher (600-fold) shift. The potency of the antagonist SQ 29,548 (1S-(1 alpha,2 beta(5Z),3 beta,4 alpha))-7-(3((2-((phenylamino)carbonyl)hydrazino)methyl)-7-oxabicyclo(2.2.1)hept-2-yl)-5-heptenoic acid) was unaffected by aorta. In coincubation experiments, arachidonic acid-challenge increased thromboxane A(2)-dependent vessel tone; picotamide increased prostacyclin and reduced thromboxane A(2) formation and vasoconstriction. Ozagrel mimicked picotamide; aspirin (acetylsalicylic acid) reduced aorta contractility, thromboxane A(2) and prostacyclin formation. SQ 29,548 reduced vasoconstriction without affecting eicosanoids. We demonstrate the importance of redirection of eicosanoids in the mechanism of action of thromboxane A(2) inhibitors/antagonists within platelet-vascular wall interactions. These findings bear relevance in the development of novel anti-thrombotic drugs.     

Preprotachykinin A gene expression after administration of 3,4-methylene dioxymethamphetamine (Ecstasy)

This study tested the effects of 8 days of subchronic administration of 3,4-methylene dioxymethamphetamine (MDMA) (5 mg/kg b.w.) on preprotachykinin A mRNA levels in discrete rat brain regions. In situ hybridization examined preprotachykinin A mRNA levels in the core and shell of the nucleus accumbens, the islands of Calleja, the olfactory tubercle, the dorsal and ventral caudate–putamen, the bed nucleus of the stria terminalis, the medial preoptic area, the medial habenular nucleus and in the postero-dorsal part of the medial amygdala. Higher levels of preprotachykinin A mRNA were found in the core and shell of the nucleus accumbens, in the islands of calleja, in the olfactory tubercle, in the bed nucleus of the stria terminalis, in the medial habenular nucleus and the postero-dorsal part of the medial amygdala, compared to control animals. Conversely, increased preprotachykinin A mRNA levels were observed in the dorsal and ventral caudate–putamen in MDMA treated when compared to control rats. In the social memory test, MDMA significantly impaired rats' short-term working memory. These results show that chronic exposure to MDMA strongly affects preprotachykinin A mRNA levels in discrete rat brain regions. These changes occur in experimental conditions in which working memory is markedly reduced, suggesting that changes in gene expression of tachykinin mechanisms may contribute to the effects of MDMA on memory function.     

Measurement of warfarin in plasma by high performance liquid chromatography (HPLC) and its correlation with the international normalized ratio

The measurement of plasma warfarin is required to investigate non-compliance, resistance to anticoagulation, drug metabolism and pharmacokinetic. Methods so far described are based on extraction of warfarin from plasma followed by reversed-phase HPLC. Extraction is the crucial step and may be performed in liquid- or solid-phase. The latter requires the preparation of columns, which makes the procedure variable. We investigated the suitability of the ready-for-use commercial cartridges for sample preparation. The method displayed between-run CV of 11.8%. Recovery was 99%. The coefficients of correlation between warfarin concentration in 50 patients and weekly dosage or INR were 0.55 (p<0.0001) or 0.25 (p=0.079).     

Study of motor function development at 8 and 12 months of age in preterm and at term children

OBJECTIVE: To compare the development of motor function in children born preterm with those born at term, at 8 and 12 months of age. To investigate the relation of motor function quality at the age of 8 months with motor ability at 12 months. METHOD: Thirty-two children participated in this study: 16 were born preterm (risk group) and 16 were born at term (control group). The spontaneous movements of the children were assessed at 8 months and their mobility skills and independence were assessed at 12 months (corrected ages for the preterm group), using standardized developmental tests (AIMS and PEDI, respectively). Data were analysed using independent t-tests (between-group comparison) and Pearson correlation coefficients (within-group comparison). RESULTS: There was no significant difference in motor function, between those born preterm with those born at term, either at 8 or at 12 months of age. In the control group, there was significant association (r=0.67; p=0.004) between movement at 8 months and mobility skills at 12 months. In the risk group, there was significant relationship between skills and independence in mobility, at 12 months corrected age (r=0.80; p=0.0001). CONCLUSION: Preterm born children, without other disorders and with age correction, might show a similar motor development as those born at term. The path for the acquisition of motor abilities in preterm born children appears to differ among those infants.     

High relative risk of a second pulmonary cancer in patients affected by laryngeal cancer: Differences by specific site of occurrence and lung cancer histotype

The frequency of a second primary lung tumor in patients affected by laryngeal cancer has been evaluated on the basis of 128,532 biopsies and 27,753 autopsies carried out from January 1, 1979 through December 31, 1988. Among these cases, 432 laryngeal cancers and 44 synchronous or metachronous pulmonary cancers have been detected (7 during life, 37 at autopsy). The highest risk of developing a lung tumor has been evidenced in patients affected by supraglottic cancer during the first 2 years of follow-up (relative risk [RR]: 32.56 for supraglottic patients versus 5.55 for glottic patients). This is particularly true of patients affected by multicentric supraglottic tumors (RR: 62.5). A significant hyperfrequency of undifferentiated lung cancers also has been noted in supraglottic patients (RR: 45.45 for supraglottic versus 14.28 for glottic patients). The information provided by autopsy allows for a more realistic and detailed outlining of the issue of tumor multiplicity, stressing the importance of strict preventive and follow-up protocols.     

Relationship between dementia and nutrition-related factors and disorders: an overview

This review gives a brief overview of the main types of dementia and summarizes current thinking on the relationship between nutritional-related factors and disorders, and dementia. Dementia is a multi-factor pathological condition, and nutrition is one factor that may play a role on its onset and progression. An optimal intake of nutrients doesn't protect people from dementia. However, studies in this area show that inadequate dietary habits, which are of particular concern in elderly populations, may increase the risk of developing a number of age-related diseases, including disorders of impaired cognitive function. They show that a deficiency in essential nutrients, such as certain B complex vitamins, can result in hyperhomocysteinemia, a well-known risk factor for atherosclerosis and recently associated with cognitive impairment in old age. A deficiency of antioxidants such as vitamins C and E, and beta-carotene, as well as nutrition-related disorders like hypercholesterolemia, hypertension, and diabetes, may also have some role in cognitive impairment. These factors can be present for a long time before cognitive impairment becomes evident, therefore they could be potentially detected and corrected in a timely manner.