Injuries in youth track and field are perceived to have multiple-level causes that call for ecological (holistic-developmental) interventions: A national sporting community perceptions and experiences.

Engaging in competitive sports as a youth can have many health benefits, but recent studies also report a high risk for injury. The long-term purpose of this Swedish research program is to develop a framework for safe track and field training for young athletes (aged 12-15 years). The aim of this study was to establish what is perceived to contribute and cause injuries in youth track and field by compiling the best available experiential knowledge about the underlying factors and use this knowledge to identify appropriate areas to handle these in practical ways. Nine focus group interviews with in total 74 participants and confirming interviews with five individuals were performed in seven Swedish regions. Qualitative research methods were used for data analysis. Injuries in youth athletes were not considered to be strictly the result of individual factors but rather the result of the interactions between factors at different levels. Three major factors emerged as follows: Insufficient knowledge for athletic development in daily practice; shortsighted communities of practice and sports policies not adjusted to youth; and societal health behaviors. The experiential knowledge in the national sporting community suggests that if effective and sustainable injury prevention processes are to be implemented for youth track and field, an ecological (holistic-developmental) approach to injury prevention is needed. Such an approach allows a longitudinal development-focused strategy for prevention that spans an athlete's entire career.

Predictive performance of telenursing complaints in influenza surveillance: a prospective cohort study in Sweden.

Syndromic data sources have been sought to improve the timely detection of increased influenza transmission. This study set out to examine the prospective performance of telenursing chief complaints in predicting influenza activity. Data from two influenza seasons (2007/08 and 2008/09) were collected in a Swedish county (population 427,000) to retrospectively determine which grouping of telenursing chief complaints had the largest correlation with influenza case rates. This grouping was prospectively evaluated in the three subsequent seasons. The best performing telenursing complaint grouping in the retrospective algorithm calibration was fever (child, adult) and syncope (r=0.66; p<0.001). In the prospective evaluation, the performance of 14-day predictions was acceptable for the part of the evaluation period including the 2009 influenza pandemic (area under the curve (AUC)=0.84; positive predictive value (PPV)=0.58), while it was strong (AUC=0.89; PPV=0.93) for the remaining evaluation period including only influenza winter seasons. We recommend the use of telenursing complaints for predicting winter influenza seasons. The method requires adjustments when used during pandemics.

Drug-induced DNA hypermethylation and drug resistance in human tumors.

Drug-induced DNA hypermethylation was observed to constitute one component of the response of human tumor cells to toxic concentrations of commonly used cancer chemotherapy agents. In both human lung adenocarcinoma cells (HTB-54) and human rhabdomyosarcoma cells (CCl-136), pulse exposures to the topoisomerase II inhibitors etoposide and nalidixic acid; to the antibiotic doxorubicin; to the microtubule inhibitors vincristine, vinblastine, and colchicine; to the DNA cross-linking agent cisplatinum; to hydroxyurea; and to the antimetabolites 1-beta-D-arabinofuranosylcytosine, 5-fluorouracil, 5-fluorodeoxyuridine, and methotrexate were associated with profound drug-induced DNA hypermethylation. Exposure of human T-lymphocytes (MOLT-4) to toxic pulse doses of 3'-azidodideoxythymidine was associated with similar drug-induced DNA hypermethylation. In every case, drug-induced DNA hypermethylation was observed only when the degree of DNA synthesis inhibition caused by the drug exceeded 90% and when drug levels or duration of exposure was sufficient to kill 90-100% of exposed cells. Drug-induced DNA hypermethylation was shown not to represent a tissue culture phenomenon, since it occurred in vivo during high-dose 1-beta-D-arabinofuranosylcytosine and hydroxyurea treatments in two leukemic patients. Drug-induced alterations in DNA methylation were frequently biphasic, with hypomethylation occurring at drug concentrations which produced mild DNA synthesis inhibition and which killed less than 50% of exposed cells. Exposure to the alkylating agents 1,3-bis(2-chloroethyl)-1-nitrosourea and cyclophosphamide and to the antimetabolites 5-azadeoxycytidine and 6-thioguanine was associated with DNA hypomethylation at all studied concentrations in HTB-54 cells. Drug-induced DNA hypermethylation could be blocked by preexposure to hypomethylating agents administered at nontoxic to mildly toxic concentrations. Drug-induced DNA hypermethylation may be capable of creating drug-resistant phenotypes by inactivating genes the products of which are required for drug cytotoxicity. Perhaps paradoxically, drug-induced DNA hypermethylation may also produce a second class of drug-resistant tumor cells, characterized by overexpression of particular gene products, by potentiating the process of gene amplification.

Inhibition of protein isoprenylation and p21ras membrane association by dehydroepiandrosterone in human colonic adenocarcinoma cells in vitro.

Treatment of mice and rats with the adrenal steroid, dehydroepiandrosterone (DHEA), protects against spontaneous and chemically induced tumors. The mechanism of the chemopreventive action of DHEA, however, remains uncertain. DHEA has been reported to inhibit cholesterol biosynthesis. Mevalonic acid constitutes the basic precursor not only for cholesterol but also for a variety of nonsterol isoprenoids involved in cell growth. Certain of these nonsterol isoprenoids are utilized for posttranslational modification of proteins including p21ras. We therefore investigated the effects of DHEA upon protein isoprenylation. Twenty-four-h exposure of HT-29 SF human colonic adenocarcinoma cells to 50 microM DHEA was associated with significant incorporation of products of [3H]mevalonate metabolism into several size classes of cellular proteins. The pattern of incorporation was similar to that obtained after treatment with 25 microM lovastatin, a specific 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitor. Very little incorporation of label from [3H]mevalonate was observed in untreated cells. This suggests that [3H]mevalonate gains entrance to isoprenylation sites after treatment with DHEA or lovastatin because of depletion of endogenous mevalonate and subsequent inhibition of protein isoprenylation. Isoprenylation plays a critical role in promoting the association of p21ras with the cell membrane. Posttranslational processing and membrane association of p21ras were both found to be inhibited by DHEA. Thus, it is possible that the inhibition of isoprenylation of p21ras and other cellular proteins by DHEA may contribute to its anti-cancer effects.

Effect of 5-azacytidine and congeners on DNA methylation and expression of deoxycytidine kinase in the human lymphoid cell lines CCRF/CEM/0 and CCRF/CEM/dCk-1.

The human lymphoid cell lines CCRF/CEM/0 and the deoxycytidine kinase (dCk)-deficient CCRF/CEM/dCk- were treated with various 5-azacytidine (5-aza-C) nucleosides and the effect on DNA methylation and dCk activity were examined. 5-Azacytidine (5-aza-C), 5,6-dihydro-5-azacytidine (DHAC), 5-aza-2'-deoxycytidine (5-aza-Cdr), and 1-beta-D-arabinofuranosyl-5-azacytidine (ara-AC) reduced the DNA 5-methylcytosine level in the CEM/0 cells, down to approximately 10% of the level in untreated cells. The dCk activity was increased after treatment with the 5-aza-C nucleosides approximately 10% compared to untreated cells. In CEM/dCk- cells DNA hypomethylation between 50 and 25% of control was seen only after treatment with DHAC and 5-aza-C. No decrease in the methylation level was seen after treatment with 5-aza-Cdr or ara-AC. The dCk activity was increased up to 37% after treatment with DHAC or 5-aza-C but no increase was observed after treatment with 5-aza-Cdr or ara-AC. CEM/dCk- cells treated with DHAC showed a revertant frequency to cells expressing dCk activity of between 0.1 and 0.6%. Cloned revertant CEM/dCk- cells isolated from soft agar had dCk activity between 31 and 113% compared to the activity in untreated CEM/0 cells. This in vitro study indicates that DHAC and 5-aza-C induced dCk re-expression in the CEM/dCk- cells whereas 5-aza-Cdr and ara-AC did not.

Mechanisms of cell growth inhibition and cell cycle arrest in human colonic adenocarcinoma cells by dehydroepiandrosterone: role of isoprenoid biosynthesis.

We have previously demonstrated that the chemopreventive agent dehydroepiandrosterone (DHEA) inhibits the isoprenylation of cellular proteins by depletion of endogenous mevalonate. We now report that treatment of HT-29 SF human colonic adenocarcinoma cells with DHEA at concentrations ranging from 12.5 to 200 microM for up to 72 h inhibited growth and arrested cells in the G1 phase of the cell cycle in a time- and dose-dependent manner. Exposure to 25 or 50 microM DHEA also transiently delayed cells in G2M phase after 48 h. Addition of mevalonic acid partially overcame both the growth and cell cycle effects of 25 microM DHEA in the initial 48 h. During prolonged exposure (72 h), the addition of mevalonic acid as well as cholesterol was required to reconstitute cell cycle progression. This suggests that the depletion of endogenous mevalonate and other isoprenoids is involved in DHEA-mediated growth inhibition and cell cycle arrest.

Insight into adenosine receptor function using antisense and gene-knockout approaches.

The extensive role of adenosine in discriminating input from the extracellular environment is effected through a series of cell membrane-spanning proteins--the adenosine A1, A2A, A2B and A3 receptors. New genetic and epigenetic tools have emerged that facilitate the elucidation of the function of these receptors with greater specificity than is generally possible with traditional antagonist drugs. These tools include antisense oligonucleotides (epigenetic) and gene 'knockin' and 'knockout' mice (genetic) and are discussed in this article by Jonathan Nyce.

Antisense to NPY-Y1 demonstrates that Y1 receptors in the hypothalamus underlie NPY hypothermia and feeding in rats.

Neuropeptide Y (NPY) is a highly potent endogenous peptide which when injected into the medial hypothalamus causes spontaneous eating behaviour and an intense fall in body temperature (Tb). This study used antisense oligodeoxynucleotides (ODNs) to determine whether the Y1 subtype of NPY receptor could underlie these remarkable physiological responses. In the unrestrained rat, the ventromedial hypothalamus (VMH) which is highly reactive to NPY was injected with antisense for NPY (aNPY), Y1 receptors (aNPY-Y1) and mismatched controls (mNPY; mNPY-Y1). After cannulae were implanted bilaterally in the brain of 19 rats, 0.4 or 0.8 microgram per 0.8 microliter of the phosphorothioate synthesised ODNs were delivered to the VMH of the rats at 12 h intervals over 2 d. Only the lower dose of aNPY-Y1, but not aNPY, evoked an intense phasic rise in the Tb following each micro-injection. Simultaneously, 0.4 microgram per 0.8 microliter of aNPY-Y1, but not aNPY, suppressed feeding behaviour after a sequence of micro-injections and on the following day. Body weights and locomotor activity of the rats likewise declined concomitantly with the hyperthermia and hypophagia caused by the Y1 receptor antisense. Neither of the control ODNs for NPY or Y1 receptors injected similarly in the VMH of the rats exerted any effects on these measures. These results clearly provide convincing evidence that in the VMH the Y1 subtype of NPY receptor mediates, in part, the neuronal mechanisms responsible for spontaneous feeding and hypothermia produced by native NPY when applied directly to this structure. The concurrent decline in body weight and activity caused by aNPY-Y1 could be caused by the episodes of hyperthermia.

Induction of peroxisomal enzymes in rat liver by dehydroepiandrosterone sulfate.

Male F-344 rats, when treated with either 150 mg/kg or 300 mg/kg body weight of DHEAS for 14 days, produced a dose-dependent increase in liver weight and peroxisomal beta-oxidation activity, characteristic of peroxisomal proliferation. Contrary to previous observations in vitro, we also found a significant increase in catalase activity in rat liver with the higher dose of the steroid. Furthermore, the in vivo induction of peroxisomal beta-oxidation by DHEAS observed in our study was significantly less than reported in vitro, and also unlike previously reported in vitro results, was approximately equivalent to DHEA administered in vivo.

Effects of inhibitors of topoisomerases-I and topoisomerases-ii on DNA methylation and DNA-synthesis in human colonic adenocarcinoma cells-invitro.

Exposure of human and animal cells to inhibitors of topoisomerase I or II has recently been shown to alter gene expression and induce differentiation in a number of experimental systems. We have previously shown that nalidixic acid and novobiocin, inhibitors of topoisomerase II, induce DNA hypomethylation. Since DNA hypomethylation is frequently associated with transcriptional activation, we wished to further explore the relationship between inhibition of DNA topoisomerases and enzymatic DNA methylation. When HT-29 human colonic adenocarcinoma cells were exposed to the specific topoisomerase II inhibitor teniposide (VM-26), a dose-dependent hypomethylation of DNA was observed during the window of drug treatment. Exposure to the topoisomerase I inhibitor camptothecin (CPT) produced a small but not statistically significant trend toward DNA hypomethylation. CPT-treated cells were found to have up to 19 fold increased levels of topoisomerase II protein, which may have compensated for decreased levels of non-drug-bound topoisomerase I. Both VM-26 and CPT were found to increase [H-3]thymidine incorporation into DNA when administered in low dose (0.5 muM VM-26; 8 nM CPT). Combination of VM-26 and CPT (0.5 muM and 8 nM, respectively) produced DNA hypomethyltion, a synergistic increase in [H-3]thymidine incorporation, and an increasing number of cells entering a higher DNA ploidy cycle. Since VM-26 interferes with the DNA strand breakage-reunion reaction by stabilizing a topoisomerase II-relaxed DNA complex, our results suggest that DNA existing in this form may be a poor substrate for DNA methylase. Topoisomerase inhibitor-induced DNA hypomethylation may offer a possible explanation for the induction of differentiation observed upon exposure to this family of drugs. Altered topoisomerase activity occurring during the process of tumor progression may also provide a link between the induction of polyploidy, DNA hypomethylation and aberrant gene expression frequently observed in tumor cells.

Autoradiographic evidence that intrastriatal administration of adenosine A(1) receptor antisense oligodeoxynucleotide decreases adenosine A(1) receptors in the rat striatum and cortex.

In this study, the effect of a phosphorothioated A(1) adenosine receptor antisense oligodeoxynucleotide on A(1) receptor density and mRNA in the striatum and cortex of rats was determined. Receptor autoradiography and in situ hybridization revealed a reduction in striatal and cortical A(1) receptor density and cortical A(1) receptor mRNA, respectively, in antisense-treated brains but not in those treated with a mismatch oligonucleotide. There was no change in A(2) receptor binding. These data imply that the corticostriatal pathway synthesizes A(1) receptors and transports them to its terminals.

RASONs: a novel antisense oligonucleotide therapeutic approach for asthma.

Inhalation based approaches enable the local delivery of antisense oligonucleotides (ASONs) to the respiratory tract and thus facilitate the ability of ASONs to target and modulate the activity of discordantly expressed respiratory disease genes. Studies involving EPI-2010, a respirable antisense oligonucleotide (RASON), targeting the adenosine A(1) receptor, a G-protein-coupled-receptor (GPCR) that plays an important role in the aetiology of asthma, demonstrate that ASON therapeutics can be delivered directly to the lung as an aerosol. EPI-2010 has been shown to inhibit adenosine A(1) receptor expression and significantly improve allergen-induced airway obstruction and bronchial hyper-responsiveness in animal models of human asthma. Absorption, tissue distribution, metabolism and excretion (ADME) and safety studies of aerosolised EPI-2010 suggest that phosphorothioate RASONs can be delivered to target respiratory tissues in low, safe, efficacious and long-acting doses. This supports the concept that RASONs offer the potential to address a variety of respiratory targets including those for which approaches employing systemic distribution and systemic bioavailability of the therapeutic agent may be undesirable. In addition, our studies with EPI-2010 indicate that the RASON approach may represent a technology that is uniquely positioned to address the challenges of the post-genome era in respiratory drug discovery, since it enables simultaneous in vivo target validation and antisense therapeutic discovery in an accelerated timeframe.

NPY-Y1 receptor antisense injected centrally in rats causes hyperthermia and feeding.

The central actions of neuropeptide Y antisense oligodeoxynucleotide (aNPY) and NPY-Y1 receptor antisense (aNPY-Y1) on body temperature (Tb), feeding and body weight of unrestrained rats were determined by the repeated intracerebroventricular (i.c.v.) injection of 0.5 microgram doses. aNPY-Y1 caused intense phasic rises in Tb, lowered body weight and caused transient feeding. aNPY increased food intake paradoxically, accompanied by a gain in body weight but did not affect Tb. Circadian activity was unaffected by either antisense oligodeoxynucleotide, and the mismatched NPY (mNPY) was without effect. These results show that NPY-Y1 receptors underlie the central thermolytic action of NPY, since aNPY-Y1 induces hyperthermic responses. Overall, the functional reduction in NPY activity by aNPY might cause a compensatory de novo synthesis of NPY in structures remote from the ventricles to augment feeding behavior.

Intravenous NPY (27-36)-D decreases cardiac output in conscious Sprague-Dawley rats.

Intravenous (IV) administration of NPY (27-36)-D, a substituted carboxyterminal fragment of neuropeptide Y (NPY), decreases mean arterial pressure (MAP) in normo-and hypertensive rats by a mechanism partially involving histamine receptors. The purpose of this study is to further characterize the cardiovascular effects of NPY (27-36)-D. NPY (27-36)-D dose-dependently decreased MAP, cardiac output, and stroke volume without significantly altering peripheral resistance. Myocardial contractility diminished by 151.2 +/- 31.8, 529.6 +/- 182.5, and 495.4 +/- 66.7 mmHg/s2 in rats treated with 300, 500, and 750 nmol/kg NPY (27-36)-D, respectively. Therefore, NPY (27-36)-D modifies MAP, in part, by a reversible negative inotropic effect on the heart.

Hypotensive effects of [D-Tyr27,36, D-Thr32]Neuropeptide Y (27-36).

An analogue of the 10 C-terminal amino acids of neuropeptide Y (NPY) containing three D-isomeric substitutions (27-36-D) has been synthesized and its cardiovascular activity studied in Sprague-Dawley (SD) and spontaneously hypertensive (SHR) rats. Intravenous administration of 1000 nmol/kg 27-36-D decreases MAP in SHR (-59.9 +/- 5.0 mmHg) and SD rats (-44.4 +/- 4.7 mmHg). The hypotension produced by 1000 nmol/kg 27-36-D diminished by 71.2% following pretreatment with the histamine receptor antagonist diphenhydramine, although histamine depletion with compound 48/80 does not significantly alter this hypotension. These data suggest that NPY (27-36)-D produces a profound and sustained hypotension in two strains of rat which is partially attributable to activity at histamine receptors.

Respirable antisense oligonucleotide (RASON) therapy for allergic asthma.

A new technology for treating respiratory disease, respirable antisense oligonucleotides (RASONs), has recently been developed by our group. RASONs are short, single-stranded nucleic acids, generally modified to reduce degradation. They differ from traditional drugs, which usually antagonise preformed proteins already functioning in a disease process. Instead, RASONs can attenuate the expression of disease-associated genes by targeting the messenger RNA (mRNA). Delivered directly to the target tissue, the lung, they avoid the problems of ineffective delivery encountered by other routes of administration. When an adenosine A(1) antisense oligonucleotide was delivered to the lungs of allergic rabbits with up-regulated A(1) adenosine receptors, desensitisation to the bronchoconstrictor effects of adenosine, histamine and a common aeroallergen (dust mite) occurred. The effect on A(1) receptors persisted on average for nearly 7 days. RASON (the phosphorothioate antisense oligonucleotide EPI-2010) administered in low dosage was evenly distributed throughout the lung (with no detectable systemic active metabolites), and was excreted primarily in urine. These results demonstrate that RASONs can be efficiently and effectively delivered to the peripheral lung. They potently and selectively attenuate the expression of disease-associated genes, an approach to therapy which is now being extended to other potentially important mediators of bronchial asthma.

Pharmacodynamic and DNA methylation studies of high-dose 1-beta-D-arabinofuranosyl cytosine before and after in vivo 5-azacytidine treatment in pediatric patients with refractory acute lymphocytic leukemia.

The primary development of clinical resistance to 1-beta-D-arabinofuranosyl cytosine (ara-C) in leukemic blast cells is expressed as decreased cellular concentrations of its active anabolite. Correlations exist between the cellular concentrations of 1-beta-D-arabinofuranosyl cytosine 5'-triphosphate (ara-CTP) in leukemic blast cells and inhibition of DNA synthetic capacity with the clinical response to high-dose cytosine arabinoside (HDara-C). 5-Azacytidine (5-Aza-C) and its congeners are potent DNA hypomethylating agents, an action closely associated with the reexpression of certain genes such as that for deoxycytidine kinase (dCk) in ara-C-resistant mouse and human leukemic cells. Reexpression of dCk could increase the cellular ara-CTP concentrations and the sensitivity to ara-C. A total of 17 pediatric patients with refractory acute lymphocytic leukemia (ALL) received a continuous infusion of 5-Aza-C at 150 mg/m2 daily for 5 days after not responding to (13/17) or relapsing from (4/17) an HDara-C regimen (3 g/m2 over 3 h, every 12 h, x 8 doses). Approximately 3 days after the end of the 5-Aza-C infusion, the HDara-C regimen was given again with the idea that the induced DNA hypomethylation in the leukemic cells may have increased the dCk activity and that a reversal of the tumor drug resistance to ara-C could have occurred. Deoxycytidine kinase (expressed as cellular ara-CTP concentrations) in untreated blasts, DNA synthetic capacity (DSC), and the percentage of DNA methylcytidine levels were determined before and after 5-Aza-C administration. Cellular ara-CTP was enhanced to varying degrees in 15 of 16 patients after 5-Aza-C treatment. The average cellular concentration of ara-CTP determined in vitro by the sensitivity test was 314 +/- 390 microM, 2.3-fold higher than the average value before 5-Aza-C treatment. In 12 patients in whom the DNA methylation studies were completed before and after 5-Aza-C treatment, the average DNA hypomethylation level was 55.6% + 15.8% of pretreatment values (n = 13; mean +/- SD). DSC showed a profound decline in 2/9 evaluable patients who achieved a complete response (CR) after this regimen. The data suggest that treatment with a cytostatic but DNA-modulatory regimen of 5-Aza-C causes DNA hypomethylation in vivo, which is associated with dCk reexpression in the patients' leukemic blasts. The partial reversal of drug resistance to ara-C by 5-Aza-C yielded two CRs in this poor-prognosis, multiply relapsed patient population with refractory ALL.(ABSTRACT TRUNCATED AT 400 WORDS)

Intrastriatal adenosine A1 receptor antisense oligodeoxynucleotide blocks ethanol-induced motor incoordination.

Intrastriatal administration of a 21-mer phosphorothioate antisense oligodeoxynucleotide targeting the adenosine A1 receptor blocked ethanol-induced motor incoordination in the rat and reduced striatal adenosine A1 receptor content, as judged by specific binding of the A1-specific ligand 8-cyclopentyl-1,3-dipropylxanthine (Bmax = 0.350 +/- 0.07, Kd = 1.87 +/- 0.50 nM). No effect upon striatal adenosine A2 receptor content was observed (Bmax = 0.415 +/- 0.04, Kd = 13.13 +/- 1.25 nM) with the A2-specific ligand 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine. A mismatched control oligodeoxynucleotide of identical G-C base composition and general sequence structure was without effect on adenosine A1 receptor (Bmax = 0.666 +/- 0.11, Kd = 1.32 +/- 0.27 nM) or adenosine A2 receptor content (Bmax = 0.501 +/- 0.08; Kd = 14.65 +/- 1.82 nM) or ethanol-induced motor incoordination. These results confirm an important role of the striatal adenosine A1 receptor in mediating certain motor-related physiological effects of ethanol.

Anorexic action of a new potential neuropeptide Y antagonist [D-Tyr27,36, D-Thr32]-NPY (27-36) infused into the hypothalamus of the rat.

Neuropeptide Y (NPY) produces a vigorous feeding response in several species when it is injected into hypothalamic structures involved in eating behavior. The purpose of this study was to determine whether a unique carboxy terminal fragment of NPY would alter the pattern of eating induced in the rat either by NPY injected into the hypothalamus or by a 24-h period of food deprivation. In this case, two L-tyrosine residues and one L-threonine residue of the NPY27-36 fragment were transformed to their D-conformation to produce [D-Tyr27,36,D-Thr32]-NPY (27-36), i.e., D-NPY27-36. Guide cannulae for microinjection were implanted stereotaxically just dorsal to the paraventricular nucleus (PVN) or ventromedial hypothalamus (VMH) of 24 adult male Sprague-Dawley rats. Following postoperative recovery, a microinjection of artificial CSF or 1.1 microgram or 3.3 micrograms of a peptide was made directly into the PVN or VMH as follows: native NPY; D-NPY27-36; or [L-Tyr27,36, L-Thr32]-NPY (27-36), i.e., L-NPY27-36. Food intakes were measured at intervals of 0.25, 0.5, 1.1, 2.0, 4.0, and 24 h. When D-NPY27-36 was microinjected at NPY reactive sites in the PVN or VMH of the rat 15 min before a similar microinjection of NPY, the intense eating response induced by the peptide was reduced significantly. Not only was the effect dose dependent, but D-NPY27-36 also augmented the latency to feed. A mixture of the two doses of NPY and D-NPY27-36 injected at the same hypothalamic loci did not attenuate the intake of food but tended to enhance the feeding response in the rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical modulation of combined radiation and 5-fluorouracil treatment of murine tumors by d,l-leucovorin.

Experiments were designed to establish whether the response of the Lewis lung tumor (LLca) to combined 5-Fluorouracil (5-FU) and radiation could be enhanced by the addition of the reduced folate leucovorin (LV) to the treatment protocol. Twenty-four hr after the tumors received a single dose of from 2.0 to 8.0 Gy of X-rays, the tumor-bearing animals were treated with a 5 day schedule of 10 mg/kg LV + 30 mg/kg 5-flourouracil (q 24 hr) in which LV preceded the 5-FU by 60 minutes. Under these time/dose configurations, no evidence of treatment-limiting gastrointestinal or hematopoietic toxicity was observed with the LV + 5-FU treatment. Following radiotherapy alone, tumor growth delays (TGDs) ranging from 1 to 6.5 days were observed with X-ray doses of from 2.0 to 8.0 Gy, respectively. When the radiotherapy was followed by the administration of 5-FU (q24 hr x 5) alone, a modest increase in the tumor response was observed; TGD increased from 1.0 to 2.0 days with 2.0 Gy and from 6.5 to 8.5 days with 8.0 Gy of X-rays. The addition of LV to the 5-FU schedule, however, resulted in a significant enhancement of the response of the tumor to the combined radiation + 5-FU treatment. TGDs increased from 1.0 to 8.0 days with a radiation dose of 2.0 Gy and from 6.5 to 34.5 days with a dose of 8.0 Gy. When administered as single agents, 5-FU and 2.0 Gy resulted in only a modest response by the LLca tumor (TGDs = 1.0 day), while LV had no effect on tumor growth. These observations, therefore, suggest that biochemical modulation of 5-FU by LV can be realized in vivo and that this biochemical modulation may be valuable in more conventional clinical schedules using combined radiation and 5-FU treatment.