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Objectives: Sodium salicylate (NaSal) can disturb cell viability by affecting the activity of multiple cellular molecules. In this work, we investigated the involvement of stress-responsive kinase GCN2 in regulating cell death and expression of stress genes in mouse embryonic fibroblasts (MEFs) upon exposure to NaSal., Methods: Cell viability was assayed using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) method, and apoptosis was evaluated by annexin V and propidium iodide staining. A polymerase chain reaction (PCR) array approach was used to analyse differential expression of a panel of 84 endoplasmic reticulum (ER) stress-associated genes. Gene reporter assays were carried out to determine activity of ER stress element (ERSE), and the protein levels of activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) were determined by western blot., Key Findings: NaSal treatment resulted in reduction of cellular viability and induction of apoptosis in wild-type but not Gcn2(-/-) cells. Many genes with important functions in protein synthesis/degradation, transcriptional regulation and apoptosis were induced by NaSal and most of these were dependent on GCN2. The activation of ERSE within Ddit3 and the production of CHOP and ATF6 induced by NaSal required GCN2., Conclusions: Our data provide evidence for the involvement of GCN2 in apoptosis and gene expression triggered by NaSal, and contributes to the understanding of molecular events occurring in NaSal-treated cells., (© 2012 The Authors. JPP © 2012. Royal Pharmaceutical Society.)

Objectives: A hydrotropic formulation containing a percutaneous enhancer was developed for the transdermal formulation of a water-soluble drug and the solubilizing mechanisms of a percutaneous enhancer in water by a hydrotropic agent were investigated. The enhancement effect was also compared with the hydrotropic formulation and the other formulations using ethanol, propylene glycol or mixed micelles., Methods: Sodium salicylate (SA) and sodium benzoate (BA) were selected as hydrotropic agents, and polyol fatty acid ester (POFE) and 5-fluorouracil (5-FU) were selected as a percutaneous enhancer and a water-soluble drug, respectively. Near-infrared (NIR) spectrophotometric and ¹H NMR spectroscopic studies were carried out to investigate the solubilizing mechanisms. The mean particle size in the hydrotropic formulation was measured. The in-vitro skin permeation of 5-FU and the accumulation in the skin of propylene glycol monocaprylate (PGMC), one of the monoesters of POFE, from the hydrotropic formulation or the other formulations were investigated by using Franz-type diffusion cell., Key Findings: The presence of SA and BA had a visible effect on the O-H stretching band of water in the NIR region. The surface tension of SA and BA aqueous solutions was found to decrease with an increase in SA or BA concentration. Although SA interacted with PGMC in the presence of water, it did not interact with PGMC in the absence of water. Mean particle size in a solution consisting of 5% (v/v) PGMC and 30% SA aqueous solution was approximately 14 nm. ¹H NMR spectroscopic studies indicated that the hydrotropic salts formed aggregates with which PGMC interacted from the outside. The hydrotropic formulation prepared in this study enhanced skin permeation of 5-FU when compared with the other formulations., Conclusions: SA and BA solubilized monoesters of POFE in water, and SA interacted with PGMC in water. The hydrotropic formulation prepared in this study significantly enhanced skin permeation of 5-FU compared with the other formulations. The results suggest that a hydrotropic formulation containing PGMC may be a useful transdermal formulation for water-soluble drugs., (© 2011 The Authors. JPP © 2011 Royal Pharmaceutical Society.)

Objectives: This study tested whether sodium para-amino salicylic dihydrate, an antibacterial drug for tuberculosis, could block manganese-induced apoptosis in SK-N-MC neurons., Methods: Cell viability, Hoechst staining, dichlorofluorescin diacetate analysis for reactive oxygen species measurement, and immunoblotting were performed., Key Findings: In vitro, manganese chloride significantly decreased the viability of SK-N-MC cells, accompanied by apoptotic features such as changes in nuclear morphology. Sodium para-amino salicylic dihydrate inhibited these apoptotic characteristics through reducing intracellular reactive oxygen species generation, protecting mitochondrial membrane potential and caspase-3 activation., Conclusions: Sodium para-amino salicylic dihydrate inhibits manganese-induced apoptosis in neurons and may reduce manganese-mediated neurodegeneration.

Oxymorphone is a potent opioid analgesic. Oral administration of oxymorphone to rats at doses >or= 20 mg/kg and mice at 500 mg/kg produced an increase in micronucleated polychromatic erythrocytes (MPCEs). Oxymorphone does not produce chromosome aberrations in vitro, suggesting that the increased MPCEs in vivo may involve indirect mechanisms. Opioids are known to affect thermoregulatory mechanisms. Changes in body temperature can increase the incidence of MPCEs in rodents. Studies were conducted to examine the relationship between increased MPCEs in rats given oxymorphone and changes in body temperature. Single oral doses of oxymorphone associated with increased MPCEs (20 and 40 mg/kg) also produced a marked, rapid increase in body temperature. When animals were pretreated with sodium salicylate, peak body temperature was lower and returned to baseline more quickly than when oxymorphone was given alone. MPCEs were evaluated in rats after administration of oxymorphone (40 mg/kg) alone or following pretreatment with an oral dose of sodium salicylate. Oxymorphone alone produced a statistically significant increase in the incidence of MPCEs (3.6 per 1000 polychromatic erythrocytes vs. 0.4 in controls). The number of MPCEs in animals pretreated with sodium salicylate was similar to controls. Sodium salicylate alone had no effect on the number of MPCEs. Systemic oxymorphone exposure was not affected by sodium salicylate pretreatment; maximum plasma concentration (C(max)) and area-under-the-curve values were similar after administration of oxymorphone alone or following pretreatment with sodium salicylate. These results indicate that the increased incidence of MPCEs following oxymorphone administration is directly related to increased body temperature.

Decreased functional beta-cell mass in type 1 and type 2 diabetes is due to beta-cell apoptosis and impaired secretory function suggested to be mediated, in part, by immune- and/or high-glucose-induced production of IL-1beta acting through the nuclear factor kappaB (NFkappaB)/Fas pathway. The aim of this study was to determine whether two drugs believed to block NFkappaB activation, the thiazolidinedione (glitazone) pioglitazone and the nonsteroidal antiinflammatory drug sodium salicylate, can protect human beta-cells against the toxic effects of IL-1beta and high glucose in vitro. Human islets were maintained in culture 2-4 d at 100 mg/dl (5.5 mm) glucose with or without (control) IL-1beta or at 600 mg/dl (33.3 mm) glucose. IL-1beta and 600 mg/dl glucose increased beta-cell apoptosis and abolished short-term glucose-stimulated insulin secretion. Both drugs protected partially against loss of glucose-stimulated insulin secretion and prevented completely increased apoptosis caused by IL-1beta or 600 mg/dl glucose. IL-1beta secretion from islets was increased by 4-d culture at 600 mg/dl, and this was blocked by pioglitazone. Both drugs prevented activation of beta-cell NFkappaB by high glucose. Pioglitazone and sodium salicylate thus protect human islets against the detrimental effects of IL-1beta and high glucose by blocking NFkappaB activation and may therefore be useful in retarding the manifestation and progression of diabetes.

Abnormal vascular smooth muscle cell (VSMC) proliferation plays an important role in the pathogenesis of both atherosclerosis and restenosis. Recent studies suggest that high-dose salicylates, in addition to inhibiting cyclooxygenase activity, exert an antiproliferative effect on VSMC growth both in-vitro and in-vivo. However, whether all non-steroidal anti-inflammatory drugs (NSAIDs) exert similar antiproliferative effects on VSMCs, and do so via a common mechanism of action, remains to be shown. In this study, we demonstrate that the NSAIDs aspirin, sodium salicylate, diclofenac, ibuprofen, indometacin and sulindac induce a dose-dependent inhibition of proliferation in rat A10 VSMCs in the absence of significant cytotoxicity. Flow cytometric analyses showed that exposure of A10 cells to diclofenac, indometacin, ibuprofen and sulindac, in the presence of the mitotic inhibitor, nocodazole, led to a significant G0/G1 arrest. In contrast, the salicylates failed to induce a significant G1 arrest since flow cytometry profiles were not significantly different from control cells. Cyclin A levels were elevated, and hyperphosphorylated p107 was present at significant levels, in salicylate-treated A10 cells, consistent with a post-G1/S block, whereas cyclin A levels were low, and hypophosphorylated p107 was the dominant form, in cells treated with other NSAIDs consistent with a G1 arrest. The ubiquitously expressed cyclin-dependent kinase (CDK) inhibitors, p21 and p27, were increased in all NSAID-treated cells. Our results suggest that diclofenac, indometacin, ibuprofen and sulindac inhibit VSMC proliferation by arresting the cell cycle in the G1 phase, whereas the growth inhibitory effect of salicylates probably affects the late S and/or G2/M phases. Irrespective of mechanism, our results suggest that NSAIDs might be of benefit in the treatment of certain vasculoproliferative disorders.

Background: Nuclear factor-kappaB (NF-kappaB) is a transcription factor involved in a number of signalling pathways in many cell types. NF-kappaB in mice has been implicated as an important regulator of keratinocyte proliferation and differentiation., Objectives: To evaluate the role of NF-kappaB in keratinocyte growth in human beings, we examined its expression in keratinocytes both in culture and in situ, and studied the relationship between NF-kappaB activation and the inhibition of keratinocyte proliferation induced by known modulators of keratinocyte growth., Methods: The expression of subunits of the NF-kappaB family was examined in human skin, primary cultured keratinocytes and an immortalized keratinocyte line by immunohistochemistry and reverse transcriptase-polymerase chain reaction analysis. NF-kB activation was examined in keratinocytes treated with various modulating agents by electrophoretic mobility shift assay (for DNA-binding activity) and by immunocytochemistry (nuclear translocation). The proliferative capacity of treated keratinocytes was also examined by 3H-thymidine incorporation, cell cycle analysis, and expression of Ki-67, a nuclear marker for cell proliferation. The involvement of NF-kappaB was assessed using sodium salicylate, which inhibits NF-kappaB activation., Results: The NF-kappaB subunits, p50, p65, RelB, and c-Rel (but not p52), were detected in keratinocytes and in normal epidermis at mRNA and protein levels. The four subunits were expressed in a cytoplasmic (rather than a nuclear) pattern in both basal and suprabasal keratinocytes. Phorbol myristate acetate (PMA), tumour necrosis factor alpha, and interferon gamma each activated NF-kappaB and inhibited keratinocyte proliferation. Lipopolysaccharide and dexamethasone did not activate NF-kappaB and had the least effect on proliferation. Finally, a high concentration of calcium (Ca2+) and retinoic acid each failed to activate NF-kappaB, but were potent inhibitors of keratinocyte proliferation, respectively. PMA-induced cell cycle arrest of keratinocytes was blocked by pretreatment with sodium salicylate., Conclusions: NF-kappaB is constitutively expressed in a resting state in both human cultured keratinocytes and the epidermis. Activation of NF-kappaB is required for PMA-induced keratinocyte growth arrest.

Aspirin has been reported to induce apoptosis in a variety of cell lines. In this study, we examined whether aspirin and sodium salicylate inhibit cell growth and induce apoptosis in rheumatoid synovial cells. Synovial cells were obtained from patients with rheumatoid arthritis, and the cells were treated with aspirin or sodium salicylate (0.1-10 mM) for 24 h. Cell proliferation and viability were assessed by 5-bromo-2'-deoxyuridine incorporation and by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) assay, respectively. The apoptosis of synovial cells was identified by DNA fragmentation assay and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay. Aspirin and sodium salicylate suppressed the proliferation (IC50 (concentration causing 50% inhibition of cell proliferation): 2.1 and 1.2 mM, respectively) and reduced the viability (IC50: 2.0 and 1.4 mM, respectively) of synovial cells in a concentration-dependent manner at 0.3-10 mM. Furthermore, they induced DNA fragmentation and increased the number of TUNEL-positive synovial cells. These results suggest that aspirin and sodium salicylate can inhibit the proliferation of rheumatoid synovial cells through induction of apoptosis.

The CC chemokine eotaxin is a potent eosinophil-specific chemoattractant that is crucial for allergic inflammation. Allergen-induced tumour necrosis factor (TNF) has been shown to induce eotaxin synthesis in eosinophils. Nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinases (MAPK) have been found to play an essential role for the eotaxin-mediated eosinophilia. We investigated the modulation of NF-kappaB and MAPK activation in TNF-induced eotaxin release of human eosinophils. Human blood eosinophils were purified from fresh buffy coat using magnetic cell sorting. NF-kappaB pathway-related genes were evaluated by cDNA expression array system. Degradation of IkappaBalpha and phosphorylation of MAPK were detected by Western blot. Activation of NF-kappaB was determined by electrophoretic mobility shift assay. Eotaxin released into the eosinophil culture medium was measured by ELISA. TNF was found to up-regulate the gene expression of NF-kappaB and IkappaBalpha in eosinophils. TNF-induced IkappaBalpha degradation was inhibited by the proteasome inhibitor N-cbz-Leu-Leu-leucinal (MG-132) and a non-steroidal anti-inflammatory drug sodium salicylate (NaSal). Using EMSA, both MG-132 and NaSal were found to suppress the TNF-induced NF-kappaB activation in eosinophils. Furthermore, TNF was shown to induce phosphorylation of p38 MAPK time-dependently but not extracellular signal-regulated kinases (ERK). Inhibition of NF-kappaB activation and p38 MAPK activity decreased the TNF-induced release of eotaxin from eosinophils. These results indicate that NF-kappaB and p38 MAPK play an important role in TNF-activated signalling pathway regulating eotaxin release by eosinophils. They have also provided a biochemical basis for the potential of using specific inhibitors of NF-kappaB and p38 MAPK for treating allergic inflammation.

Enteroaggregative Escherichia coli (EAggEC) are associated with both acute and persistent diarrhoea in children. Bowel colonisation due to fimbrial adherence factors appears to play a major role in the disease process. In this study, we investigated the effect of sodium salicylate and 5-aminosalicylic acid on adherence of a type strain and 40 clinical isolates of EAggEC to HEp-2 cells and erythrocytes from different species. Growth in the presence of 10 mM salicylate resulted in markedly decreased adherence to tissue culture cells with 33/40 (82.5%) isolates, and was also associated with inhibition of haemagglutination in 20/33 (60.6%) isolates. Complete or partial inhibition of adherence was also seen in two of five isolates showing localised adherence and three of five isolates with diffuse adherence. Decrease in adherence was associated with decreased or absent expression of fimbriae in 28/40 (70%) of the EAggEC isolates, although production of outer membrane proteins was not affected. Salicylates appear to inhibit adherence mediated by fimbrial adhesins.

Aspirin and sodium salicylate each inhibit to a similar extent the production of nitric oxide (NO) in the RAW 264.7 murine macrophage cell line following stimulation by either lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma). The similar potencies of aspirin and sodium salicylate indicate that acetylation of cellular macromolecules is not essential for the observed effects. The failure of added prostaglandin E2 to overcome the effects of aspirin or sodium salicylate indicates that these effects are not simply the result of inhibition of prostaglandin synthesis. The inhibition of NO production occurs irrespective of the effect of these agents on induction of nitric oxide synthase (iNOS) mRNA by LPS or IFN-gamma. Aspirin and sodium salicylate inhibit iNOS mRNA induction in LPS-stimulated cells but enhance iNOS mRNA induction in IFN-gamma-stimulated cells. In contrast, these agents consistently inhibit induction of argininosuccinate synthetase mRNA in both LPS- and IFN-gamma-stimulated cells. Concentrations of aspirin in the 3-10 mM range inhibit induced NO production and expression of iNOS protein without inhibiting induction of iNOS mRNA. Discordances between effects on NO synthesis and induction of iNOS mRNA indicate that aspirin and sodium salicylate have multiple sites of action in their effects on pathways that are involved in the production of NO by stimulated RAW 264.7 cells.

Mycophenolate mofetil, the prodrug form of the immunosuppressive agent mycophenolic acid (MPA), is currently in clinical trials evaluating its effectiveness in transplant recipients. In this study, we validated an ultrafiltration system for the reliable measurement of free MPA. Using this technique, we evaluated factors that might be important in modulating the free fraction of this drug. Human serum albumin (HSA), high concentrations of the primary glucuronide metabolite of MPA, and sodium salicylate significantly affected MPA binding. For HSA the mean +/- SE binding capacity (Bmax) and the dissociation constant (Kd) were 1095 +/- 34 mumol/L and 12.98 +/- 0.93 mumol/L, respectively. The dose for 50% inhibition (IC50) of inosine monophosphate dehydrogenase isoform II by MPA increased 5.4-fold as the concentration of HSA added to the enzyme reaction mixture increased from 0 to 50 g/L (0-724 mumol/L). Furthermore, the IC50 MPA concentration for phytohemagglutinin A-stimulated human peripheral blood mononuclear cells increased 4.8-fold when incubations were performed in the presence of 10 g/L (145 mumol/L) HSA vs no added HSA. These data support the hypothesis that the pharmacological activity of MPA is a function of unbound drug concentration.

Bismuth subsalicylate (BSS), sodium salicylate, and bismuth nitrate were compared with respect to their effects on capsular polysaccharide (CPS) production, bacterial growth inhibition, and potentiation of aminoglycoside inhibition on strains of Gram-negative bacteria. At 250 microM, BSS reduced CPS production in Klebsiella pneumoniae cultures by greater than 90% in contrast to a 36% reduction by salicylate. At 500 microM, salicylate reduced CPS by 52%, versus a 70% reduction by bismuth nitrate. Substantial reduction of CPS production by BSS occurred before bacterial growth inhibition was observed. However, BSS at 250 microM decreased cell viability by 21%, and at 1 mM by 50%. Bismuth nitrate was equally inhibitory to cell growth. Salicylate at 1 mM did not affect bacterial cell counts. The susceptibility of selected Gram-negative bacteria to aminoglycoside antibiotics was studied in the presence of BSS or salicylate. Generally, salicylate at 2.5 mM reduced the concentration of aminoglycoside required to inhibit culture growth for 24 h (IC24) by two-fold. In contrast, 700 microM BSS reduced the IC24 for amikacin four-fold for a resistant K. pneumoniae strain. At 500 microM, BSS reduced the IC24 of gentamicin seven-fold for Salmonella typhimurium. Inhibitory concentrations of amikacin or tobramycin for Enterobacter cloacae or Serratia marcescens were also reduced seven-fold with 500 microM BSS. Bismuth nitrate reduced the IC24 of tobramycin by four-fold for E. cloacae. Thus, the profound effects of BSS on CPS production and aminoglycoside potentiation were due to the additive effects of bismuth and salicylate ions, whilst its effects on growth inhibition were due to the bismuth ion.

Sodium salicylate was combined with the antibiotics amikacin, aztreonam, cefazolin, cefonicid, cefoperazone, ceftizoxime, norfloxacin, doxycycline, clindamycin, imipenem, mezlocillin and trimethoprim-sulphamethoxazole. The activity of the combinations was tested against encapsulated strains of Klebsiella pneumoniae, which differed markedly in their antibiotic susceptibility. The addition of salicylate (from 2 to 350 mg/l) to cultures increased the MIC of most antimicrobial agents from two- to four-fold, with the exception of imipenem and amikacin. Inhibition by imipenem was largely unchanged, and that of amikacin was increased in the presence of salicylate. The synergy of the combination of cefazolin and amikacin was abolished by salicylate, while the synergistic activity of imipenem and amikacin was significantly increased by salicylate. Doxycycline activity was most severely affected by salicylate as antimicrobial activity was significantly diminished at salicylate levels as low as 5 mg/l. In contrast, significant loss of inhibitory activity with other antimicrobials required at least 100 mg/l of salicylate. The clinical implications of salicylate on the sensitivity of K. pneumoniae to antimicrobials are discussed.

This study determined the effects of sodium salicylate combined with several aminoglycoside antibiotics on the growth and capsular polysaccharide (CPS) production of Klebsiella pneumoniae. Salicylate significantly enhanced in inhibitory effect of all aminoglycoside antibiotics against all bacterial strains tested. The production of CPS was decreased by 62-86% when 2.5 mM salicylate was used. Amikacin combined with salicylate reduced CPS only slightly more than salicylate alone. The chelating agents, ethylenediamine tetra-acetic acid and ethylene bis tetraacetic acid, which have similar CPS-reducing properties, did not enhance the inhibitory effect of amikacin. Noncapsular variants of strains of K. pneumoniae were as susceptible to amikacin as the fully encapsulated strains, with or without salicylate present. Therefore, the combination of salicylate and the aminoglycosides acted synergistically to inhibit K. pneumoniae growth, but the increase in antibiotic sensitivity with salicylate was not a result of a reduction in CPS production. The use of salicylate in maximum therapeutic doses may enhance the activity of aminoglycosides sufficiently to allow the dose of aminoglycoside to be reduced when infections due to K. pneumoniae are treated.

Arachidonic acid and lysophospholipids generated by glucose stimulation of phospholipase A2 may be related to the biphasic pattern of insulin secretion. Therefore, we examined the effects of glucose, exogenous phospholipase A2, lysophospholipids, and pharmacological agents which perturb the reesterification or oxygenation of arachidonic acid in superfused monolayer cultures of neonatal rat islet cells. Nordihydroguaiaretic acid (20 microM), an inhibitor of islet lipoxygenase, significantly decreased phasic glucose-stimulated insulin secretion, especially during phase 1, suggesting that stimulatory lipoxygenase metabolites of arachidonic acid contribute to the effects of glucose stimulation. Treatment with exogenous phospholipase A2 (10 mU/ml) or melittin (1.0 or 2.0 micrograms/ml) to generate arachidonic acid and lysophospholipids de novo caused a monophasic release of insulin, followed by a gradual decline in insulin secretion despite the continued presence of these agonists. Conversely, p-hydroxymercuribenzoate (15, 30, and 50 microM), which blocks the reacylation of lysophospholipids with arachidonic acid, evoked a concentration-dependent biphasic stimulation of insulin secretion which was reversible. Lipoxygenase inhibition had no effect upon phase 1 secretion by p-hydroxymercuribenzoate, although it did partially reduce phase 2 secretion. However, lysophosphatidylcholine (50, 75, and 100 micrograms/ml) also caused a concentration-dependent biphasic stimulation of insulin secretion which resembled that seen with p-hydroxymercuribenzoate, suggesting that lysophospholipids were mediating the effects of p-hydroxymercuribenzoate. We speculate that during glucose stimulation of the islet, the following three phospholipase A2-initiated changes may be important: generation of lysophospholipid to stimulate directly insulin secretion, generation of arachidonic acid and lipoxygenase-mediated arachidonate metabolites, which positively modulate insulin secretion, and generation of cyclooxygenase-mediated arachidonate metabolites, which negatively modulate insulin secretion.

Plasma levels of cefoxitin, as enhanced by rectal coadministration of sodium salicylate, were reduced by concurrent administration of less than 0.5 mg mL-1 N-ethylmaleimide (NEM) or p-chloromercuriphenylsulphonic acid, sodium salt (p-CMP). Concentrations of these inhibitors above 1 mg mL-1 resulted in enhanced peak plasma values of cefoxitin. This did not occur after coadministration with either ethylenediaminetetraacetic acid (EDTA) or polyoxyethylene-23 lauryl ether (POE). Ouabain and 2,4-dinitrophenol (DNP) suppressed plasma cefoxitin levels in the presence of salicylate and the enhancing effects of EDTA and POE when EDTA and POE were administered at low doses. At higher concentrations of EDTA and POE, DNP had little effect, while ouabain had little effect on POE and only partially suppressed the effects of EDTA. Plasma concentrations of cefoxitin after coadministration with salicylate and POE together, or with EDTA and POE together, were about the same as expected from summing the plasma levels resulting from coadministration of each adjuvant individually at the same concentrations. However, combined administration of salicylate and EDTA with cefoxitin yielded plasma cefoxitin concentrations which were much higher than expected from the sum of their individual actions.

Sodium salicylate and 5-methoxysalicylate both increased the rectal absorption of insulin in dogs when co-administered with insulin in various formulations. Microenema formulations containing 4% gelatin showed the highest insulin bioavailability of the formulations studied whereas microenemas (without gelatin) and suppository formulations were not as effective in enhancing the rectal absorption of insulin.

The effect of semipurified human leukocytic pyrogen isolated in vitro from neutrophilic leukocytes was studied in awake, chair-restrained rhesus monkeys. Intravenously administered leukocytic pyrogen elicited (1) a monophasic fever of short duration and latency to onset that varied from animal to animal and (2) a febrile response that was much greater at night, when the base-line temperature is low, than during the day, when the base-line temperature is high. Intravenous indomethacin, in contrast to large intravenous doses of sodium salicylate, reduced the febrile response to leukocytic pyrogen. Rapid, repeated injections of leukocytic pyrogen prolonged the febrile response from 1 1/2 to 5 1/2 hr, at which point there was a sudden 300%-400% increase in fever increment over a 30-min period. Since the rhesus monkey is as sensitive to human leukocytic pyrogen as the rabbit, it is proposed that this primate might serve as a useful model in investigations directed toward the understanding of the pathophysiology of fever in human beings.

Five-month-old lean and obese Zucker rats were fasted for up to 7 days (lean rats) or 28 days (obese rats), and serum total and free T4 and T3 concentrations, percent free T4 and T3 by equilibrium dialysis, and the binding of [125I] T4 to serum proteins by gel electrophoresis were measured. In the lean rats, a 4- or 7-day fast resulted in significant decreases in serum total and free T4 and T3 concentrations. There was a decrease in the percent free T3 after 7 days of starvation. In contrast, a 4- or 7-day fast did not alter any of these variables in the obese rats. However, after 14 or more days of starvation, serum total T4 and T3 concentrations increased, and the percent free T4 and T3 decreased, resulting in no change in the serum free T4 or T3 concentrations in the obese rats. The percent of [125I]T4 bound to serum thyronine-binding globulin increased and the percent bound to thyronine-binding prealbumin decreased with the duration of the fast in both the lean and obese rats. The increase in serum thyronine-binding globulin binding of T4 can explain the increase in serum total T4 and T3 concentrations, the decrease in percent free T4 and T3, and the normal free hormone concentration in the long term fasted obese rats. The findings in the lean rats appear to be due to a combination of the known central hypothyroidism that occurs during 4-7 days of fasting and the fasting-induced changes in T4 binding in serum. Changes in T4 and T3 binding in serum during fasting in the rat must be considered when the effects of fasting on serum concentrations of the thyroid hormones, thyroid hormone kinetics, and the peripheral action of the thyroid hormones are evaluated.

The effect of sodium salicylate, at concentrations obtained in vivo, on the random migration and chemotactic response of neutrophils and monocytes was examined. Incubation of cells in vitro increased neutrophil migration but decreased monocyte migration. However, both neutrophil and monocyte migration were significantly increased when obtained from normal individuals after ingestion of sodium salicylate. Salicylate also partly reversed the inhibition of neutrophil migration produced by aggregated immunoglobulin bound to the filter substrate. These effects of salicylate on leucocyte function may contribute to the anti-inflammatory activity of the drug.

Sodium salicylate, disodium ethylenediaminetetraacetic acid (EDTA) and polyoxyethylene-23-lauryl ether (POE) significantly enhanced the absorption of cefoxitin from the rectum but with the following differences. The effectiveness of salicylate or EDTA was enhanced by sodium chloride, whereas the activity of POE was not. Although the ratios of plasma cefoxitin peak values to cefoxitin dose were constant with POE or EDTA, the peak to dose ratios with salicylate decreased with increasing cefoxitin concentration. Phlorizin and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited the effectiveness of salicylate, but did not influence the adjuvant action of either POE or EDTA. Although treatment with salicylate resulted in slightly less protein release than treatment with NaCl, both POE and EDTA increased the release of protein from the rectal mucosa. It appears that the effects of salicylate occur at the protein fraction of the rectal mucosa through a saturable process whereas the adjuvant action of POE and EDTA appears to involve some irreversible disruption of the membrane.

The effect of suppression of fever on viral levels in nasal washes of ferrets infected with either of two clones (7a, virulent; 64d, attenuated) of the recombinant influenza virus A/Puerto Rico/8/34-A/England/939/69 (H3N2) was studied. The febrile response was reduced by shaving the ferrets or by treating them with sodium salicylate, which had no noticeable effect on the inflammatory response. For both clones, significantly more virus was shed in the nasal washes of ferrets whose febrile response was suppressed, and the viral levels decreased less rapidly than in untreated ferrets or in those in which the treatments were ineffective.