Brain insulin growth factor-I induces diuresis increase through the inhibition of arginin-vasopressin release in aged rats.

Normal aging is associated with water homeostasis impairment, arginin-vasopressin (AVP) neuron dysfunction and cerebral insulin growth factor-I (IGF-I) expression deficit. Therefore, we aimed at investigating whether a cerebral chronic treatment of IGF-I in aged rats (26-mo) could restore diuretic function comparable with that observed in adults (3-mo). By using osmotic pumps, we have shown that in aged rats, IGF-I treatment in the third ventricle for four weeks increases water intake and restores diuresis and AVP plasma release similar with that observed in adults. The decrease in AVP plasma release induced by brain IGF-I treatment was also associated with the decrease in urinary osmolality. These results indicate that the age-dependent IGF-I deficit in the brain may be involved in the age-impaired fluid homeostasis in rats.

Age-impaired fluid homeostasis depends on the balance of IL-6/IGF-I in the rat supraoptic nuclei.

Adaptive metabolic changes associated with bacterial infections are likely to cause dehydration. Activation of hypothalamic neurons in the supraoptic nucleus that release anti-diuretic arginine-vasopressin in plasma provides water retention. Aging is characterized by arginine-vasopressin neuron hyper-activity and over-expression of pro-inflammatory cytokines like interleukin (IL)-6. Conversely, insulin-like growth factor (IGF)-I, known to exhibit anti-inflammatory properties, decreases with age. We compared activation of arginine-vasopressin neurons in adult (3 months) and aged (22 months) Wistar rats by measuring not only c-fos expression, plasma arginine-vasopressin and diuresis but also the expression of IL-6 and IGF-I in the supraoptic nuclei after intraperitoneal lipopolysaccharide injection. Aged rats displayed a heightened, shorter lasting activation of arginine-vasopressin neurons following lipopolysaccharide as compared to adults. IL-6 mRNA was 3-fold higher while IGF-I mRNA was 10-fold lower in aged than in adult rats. Brain pre-treatment with neutralizing anti-IL-6 antibodies or recombinant IGF-I in aged rats reversed lipopolysaccharide-induced anti-diuresis. These data extend the concept of neuroendocrine-immune interactions to the arginine-vasopressin neuronal system by establishing a relationship between brain IL-6/IGF-I balance and age-associated arginine-vasopressin neuronal dysfunction.

Tumor necrosis factor-alpha-induced sickness behavior is impaired by central administration of an inhibitor of c-jun N-terminal kinase.

RATIONALE: Tumor necrosis factor-alpha (TNFalpha) acts within the brain to induce sickness behavior, but the molecular mechanisms are still unknown. TNFalpha binding induces receptor trimerization, activation of c-Jun N-terminal kinase (JNK), and induction of downstream transcription factors. OBJECTIVES: We hypothesized that TNFalpha-induced sickness behavior can be blocked by a novel JNK inhibitor. METHODS: To test this idea, we used a bipartite protein consisting of a ten-amino-acid sequence of the trans-activating domain of the viral TAT protein (D-TAT) linked to a 19-amino-acid peptide that specifically inhibits JNK activation (D-JNKI-1). C57BL/6J mice were pre-treated intracerebroventricularly (i.c.v.) with D-JNKI-1 or the control peptide containing only the protein transduction domain, D-TAT. Mice were then injected centrally with an optimal amount of TNFalpha (50 ng/mouse) to induce sickness behavior. Sickness was assessed as a decrease in social exploration of a novel juvenile, an increase in duration of immobility and loss of body weight. RESULTS: Pre-treatment with D-JNKI-1 (10 ng/mouse), but not D-TAT, significantly inhibited all three indices of sickness induced by central TNFalpha. CONCLUSIONS: These findings demonstrate that D-JNKI-1 can abrogate TNFalpha-induced sickness behavior and suggest a potential therapeutic target for treating major depressive disorders that develop on a background of cytokine-induced sickness behavior.

High sensitivity differential scanning calorimetry investigation of the interaction between liposomes, lactate dehydrogenase and tyrosinase.

High sensitivity differential scanning calorimetry (HSDSC) has been used to study the interaction of the model proteins lactate dehydrogenase (LDH) and tyrosinase with dimyristoylphosphatidylcholine (DMPC) liposomes, and relate this to the thermal and physical stability of the proteins. On heating, both LDH and tyrosinase denatured irreversibly in a time-dependent manner and modified the phase transition behaviour of DMPC liposomes at all concentrations investigated. The most marked effects occurred for the pretransition rather than the main phospholipid phase transition. The effects on the bilayer are likely to result from electrostatic interactions of the hydrophilic proteins with the head-groups of DMPC molecules, whilst due to their hydrophilic nature they do not penetrate into the bilayer. Tyrosinase is more highly ionised than LDH at the pH of the investigation, which may explain why tyrosinase has a greater effect than LDH on the HSDSC scans at mg/ml protein concentrations.

The enzyme indoleamine 2,3-dioxygenase is induced in the mouse brain in response to peripheral administration of lipopolysaccharide and superantigen.

The essential amino-acid, L-tryptophan, is the precursor of serotonin. Its availability in the brain is controlled by indoleamine 2,3-dioxygenase (IDO). This enzyme is inducible by cytokines such as interferon-gamma (IFN-gamma) and is the first and rate-limiting enzyme of the catabolism pathway of tryptophan. Since induction of IDO has been proposed to mediate the influence of cytokines on mood in patients with various somatic disorders, the present study aimed at analyzing the relationships between changes in brain IDO activity and serum IFN-gamma levels in response to peripheral immune stimulation by lipopolysaccharide (LPS) and superantigen in mice. Each of these treatments induced an increase in serum IFN-gamma at 6 h post-treatment followed 24 h later by a two-fold increase in IDO activity in the brain. These results support the involvement of peripheral IFN-gamma in the control of L-tryptophan catabolism in the brain.

[Multiple sclerosis: pathogenesis and manifestations in children]. / Sclérose en plaques: pathogénie et formes de révélation chez l'enfant.

Multiple sclerosis (MS) is rare in children and occurs exceptionally before ten years. Sex ratio (girl/boy) is around 2.5 to 3, higher than in adults. Brain stem dysfunction and meningeal symptoms are more commonly first manifestations of the disease than in adults. Optic neuritis is also a frequent early manifestation. The etiology of the disease remains unclear and none of the advanced hypotheses (infectious, genetic, environmental) can by themselves explain its occurrence. There is a genetic susceptibility which is probably linked to many genes leading to a low related risk (less than two). A viral trigger mechanism in a person with a genetic predisposition is possible. New therapies result from a better understanding of the closed immune mechanisms of the disease.

An assessment of jet and ultrasonic nebulisers for the delivery of lactate dehydrogenase solutions.

The aim of this study was to investigate the suitability of commercial jet and ultrasonic nebulisers for effective delivery of the model hydrophilic protein lactate dehydrogenase (LDH). Two jet nebulisers (Pari LC Plus and Pari LC Star) and two ultrasonic nebulisers (Sonix 2000 and Omron U1) were used to nebulise LDH solutions and the effects on protein activity and protein concentration determined. The size distribution of the aerosols produced, measured by laser diffraction analysis, temperature changes during nebulisation, the time to atomise a 5 ml dose volume and the mass output of the four nebulisers were compared. A twin impinger (TI) was used to collect the nebulised protein, which was assayed for total and active protein content. There was a large variation in the median size and size distribution of the aerosols produced by each of the nebulisers from LDH and Sørensen's modified phosphate buffer, and in the time taken to reach the sputtering phase of aerosolisation. During use, the concentration of LDH increased in the Omron U1 nebuliser, but did not change significantly in the others. The temperature of the protein solution decreased by approximately 8 degrees C during jet nebulisation but increased by 3 and 10 degrees C in the Omron U1 and Sonix 2000 nebulisers, respectively. Denaturation of LDH within the nebuliser reservoir, occurred in the order Sonix>Pari LC Plus>Pari LC Star>Omron U1, whilst the deposition of active and total protein within the stages and throat of the TI was a function of the particle size of the aerosols generated and the specific device used.

Rat microglial cells secrete predominantly the precursor of interleukin-1beta in response to lipopolysaccharide.

Little is known on the forms of interleukin-1beta (IL-1beta) that are produced by microglial cells in the nervous system. Mixed glial cell cultures of rats produced IL-1beta in response to lipopolysaccharide (LPS). Using Western blot, pro-IL-1beta was found to be localized both intracellularly and in the supernatant, whereas mature IL-1beta was found only in the supernatant but in lower quantities than pro-IL-1beta. Immunocytochemistry confirmed that microglial cells are the exclusive source of IL-1beta. Blockade of the IL-1beta-converting enzyme (ICE) by Tyr-Val-Ala-Asp-aldehyde (YVAD-CHO) decreased the levels of mature IL-1beta but had no effect on pro-IL-1beta. Release of pro-IL-1beta was not associated with cell death nor with the extracellular release of ICE. Using gelatin zymography, glial cells were found to express constitutive matrix metalloproteinases (MMP) in the form of MMP-2. Exposure to LPS induced MMP-9 expression in a time-dependent manner similar to the pro-IL-1beta expression profile. MMP activation and inhibition experiments indicated a possible role of MMPs in the cleavage of pro-IL-1beta but not in the generation of mature IL-1beta. Microglial cells share with macrophages the ability to release large amounts of pro-IL-1beta of which the extracellular role remains to be determined.

Characterization of interleukin-1 receptor antagonist isoform expression in the brain of lipopolysaccharide-treated rats.

The endogenous interleukin-1 receptor antagonist is the natural inhibitor of the biological effects of interleukin-1 during inflammation. Interleukin-1 receptor antagonist refers to three isoforms: one secreted and two intracellular forms (types I and II). The objective of the present study was to investigate the expression of interleukin-1 receptor antagonist isoforms in the rat brain in vivo in response to an i.p. injection of lipopolysaccharide. The interleukin-1 receptor antagonist was studied at the messenger and protein levels by reverse transcription-polymerase chain reaction and western blot analysis, respectively. Interleukin-1 receptor antagonist messenger RNA was constitutively expressed in the brain and its expression increased in response to lipopolysaccharide. The three interleukin-1 receptor antagonist protein isoforms were up-regulated after lipopolysaccharide treatment in a time-dependent manner. Their relative expression differed according to the isoform and brain region studied. Double immunofluorescence staining revealed interleukin-1 receptor antagonist positive neurons and microglia in hippocampus 24h after lipopolysaccharide stimulation. These results demonstrate for the first time that brain cells are able to produce interleukin-1 receptor antagonist isoforms in response to a peripheral immune challenge with a predominance of the secreted over intracellular forms.

Production of interleukin-1 receptor antagonist isoforms by microglia in mixed rat glial cells stimulated by lipopolysaccharide.

Although the natural interleukin-1 receptor antagonist (IL-1Ra) has been shown to be produced by microglial cells in response to immune stimuli, nothing was known about the ability of these cells in primary culture to produce the different isoforms of IL-1Ra. Using RT-PCR, we first confirmed that mixed glial cell cultures from newborn rats respond to the cytokine inducer, lipopolysaccharide, by synthesizing IL-1Ra mRNA. Using double immunostaining, we showed that IL-1Ra was detected in microglia but not in astrocytes. Using Western blotting, we finally demonstrated that the IL-1Ra1 isoform was secreted in the supernatant of mixed glial cell cultures, and its production increased in response to lipopolysaccharide. The three different IL-1Ra isoforms were constitutively expressed in cell lysates and their levels increased after lipopolysaccharide treatment, except for IL-1Ra3. These results point to the ability of microglial cells in primary culture to produce the different isoforms of IL-1Ra.

Risk factors for second urinary tract infection among college women.

To better understand the etiology of recurrent urinary tract infection (UTI), the authors followed a cohort of 285 female college students with first UTI for 6 months or until second UTI. A first UTI due to Escherichia coli was followed by a second UTI three times more often than was a non-E. coli first UTI (24 vs. 8%; p = 0.02). In a logistic regression analysis limited to the 224 women from the University of Michigan Health Service and the University of Texas at Austin Health Service from September 1992 to December 1994, with a first UTI due to E. coli, vaginal intercourse increased the risk of a second UTI with both a different (odds ratio (OR) = 1.60, 95% confidence interval (CI): 1.19, 2.15) and the same (OR = 1.37, 95% CI: 0.91, 2.07) uropathogen, as did using a diaphragm, cervical cap, and/or spermicide (same uropathogen: OR = 1.53, 95% CI: 0.95, 2.47; different uropathogen: OR = 1.77, 95% CI: 1.22, 2.58). Condom use decreased the risk of a second UTI caused by a different uropathogen (OR = 0.68, 95% CI: 0.48, 0.99) but had no effect on a second UTI caused by the same E. coli (OR = 0.99; 95% CI: 0.66, 1.50). Type or duration of treatment was not associated with a second UTI. Although the risk of second UTI is strongly influenced by sexual behavior, women with a first UTI caused by E. coli are more likely than are those with a non-E. coli first UTI to have a second UTI within 6 months.

Discovery of disseminated J96-like strains of uropathogenic Escherichia coli O4:H5 containing genes for both PapG(J96) (class I) and PrsG(J96) (class III) Gal(alpha1-4)Gal-binding adhesins.

The pyelonephritis-associated adhesin gene papG of Escherichia coli occurs in three variants. Whereas the class II and class III variants are common among human urinary tract infection isolates, the class I allele, despite being the first cloned, has previously been found only in source strain J96. Five strains have been discovered from geographically diverse locales that, like J96, contain both the class I and class III papG alleles. One strain caused bacteremia, whereas 4 caused cystitis. Like J96, all 5 had group III capsule genes, expressed the H5 flagellar antigen and the F13 fimbrial antigen, and exhibited similar genomic patterns and virulence factor profiles. These findings demonstrate that the class I papG allele is not unique to J96 but is present in a group of extraintestinal isolates of E. coli O4:H5 that represent a disseminated virulent clonal group.

Transmission of uropathogens between sex partners.

Epidemiologic evidence and several case reports suggest that Escherichia coli causing urinary tract infection (UTI) may be transmitted between sex partners. In order to test this hypothesis, urinary, vaginal, and fecal E. coli isolates from 19 women with UTI were compared with E. coli found in random initial voids from their most recent male sex partner. E. coli was isolated from 4 of 19 male sex partners. In each case, the E. coli isolated from the man was identical by pulsed-field gel electrophoresis and bacterial virulence profile to the urinary E. coli from his sex partner.

Virulence characteristics of Escherichia coli causing first urinary tract infection predict risk of second infection.

Escherichia coli causes most urinary tract infections (UTIs) in ambulatory populations. Several bacterial virulence factors occur more frequently among urinary E. coli isolates than among fecal isolates, but none have been reported to predict risk of second UTIs. DNA hybridization was used to characterize the bacterial virulence profiles of urinary E. coli isolates from 174 women with first UTI and compared for risk of second UTI. Of the women, 28 (16%) had a culture-confirmed second UTI within 6 months of a negative test-of-cure. Three virulence factors were associated with a significantly lower risk of second UTI: cytotoxic necrotizing factor (relative risk [RR] = 0.0; 95% confidence interval [CI], 0.0, 0.42); hemolysin (RR, 0.10; 95% CI, 0.01, 0.69), and S fimbrial adhesin (RR, 0.25; 95% CI, 0.06, 1.00). Dr binding was associated with a 2-fold increased risk of second UTI (RR, 2.30; 95% CI, 1.23, 4.29). Half of all paired first and second UTI isolates from the same subject were apparently the same.

Bacterial virulence characteristics of Escherichia coli isolates from first-time urinary tract infection.

The frequency of nine potential Escherichia coli urinary tract infection (UTI) virulence factors was investigated among 216 isolates from 208 women 18-40 years old with first-time UTI. Factors were afimbrial adhesions I-IV and F1845 pili (drb), aerobactin (aer), group II capsules (kpsMT), cytotoxic necrotizing factor 1 (cnf1), alpha-hemolysin (hly), outer membrane protease T (ompT), Pap and Prs pili (prf), S fimbriae (sfa), and type 1 pili (fim). Women were enrolled at two sites. Pairwise comparisons found 14 statistically significant associations between virulence genes after correcting for multiple comparisons. This is the first report of five associations: aer and drb, kpsMT and ompT, ompT and cnf1, ompT and sfa, and prf and ompT. As ompT is not closely linked genetically to kpsMT, cnf1, prf, or sfa, ompT may be functionally linked with one or more of these other virulence factors.

First-time urinary tract infection and sexual behavior.

We studied the relation between sexual and health behaviors of women and first-time urinary tract infection (UTI). The study population was women using a university health service who were unmarried, had no UTI history, and who had engaged in sexual activity at least once. We found 86 cases of UTI, defined as one or more urinary symptoms and > or = 1,000 colony-forming units per ml urine of a known pathogen. We randomly sampled 288 controls from the student body. Vaginal intercourse increased the risk of UTI; this risk was further increased with condom use. After adjusting for vaginal intercourse with other birth control methods and recentness of current sexual partnership, a single sex act with a condom in the past 2 weeks increased UTI risk by 43%. Having a sex partner for less than 1 year vs 1 year or more, after adjustment for frequency of vaginal intercourse and birth control method, was associated with about twice the risk of UTI [odds ratio (OR) = 1.97; 95% confidence interval (CI) = 1.04-3.74]. After adjusting for frequency of vaginal intercourse, regular drinking of cranberry juice was protective against UTI (OR = 0.48; 95% CI = 0.19-1.02), whereas drinking carbonated soft drinks appeared to be associated with increased risk (OR = 2.37; 95% CI = 0.75-7.81). Using deodorant sanitary napkins or tampons was associated with a slight increase in risk of UTI (OR = 1.51; 95% CI = 0.74-3.06). Blacks had five times greater risk of UTI than whites after adjusting for frequency of vaginal intercourse (OR = 5.2; 95% CI = 1.89-24.63). We observed only modest differences in health behavior between racial groups.

Evaluation of the mass balance assumption with respect to the two-resistance model of intestinal absorption by using in situ single-pass intestinal perfusion of theophylline in rats.

Methods of analyzing drug absorption data from rat intestinal-perfusion experiments are discussed in terms of mass-transfer resistances, or reciprocal permeabilities, and mass balances. Typically, a two-resistance model is used to determine the dimensionless effective permeability (P*eff) by measuring the disappearance of drug from the perfusing solution. Unstated assumptions in two-resistance models are (1) the portal blood is under sink conditions and (2) complete transfer of drug occurs from the intestinal perfusate to the portal vein. The assumption of sink conditions is generally acceptable, because the drug concentration in portal blood is approximately two orders of magnitude less than in the perfusate. Single-pass intestinal-perfusion experiments were performed on rats with theophylline as a model compound. The drug mass leaving the intestinal perfusate was substantially less than the drug mass appearing in the portal plasma; that is, the assumption of complete transfer did not hold for theophylline in this experimental system. These data indicate that models based on the two-resistance theory can lead to overestimation of P*eff by the ratio of the drug mass leaving the perfusate to the drug mass appearing in the plasma. For compounds for which the assumption of complete transfer does not hold, a more accurate estimate of P*eff may be determined by dividing the value derived from perfusate data by the mass balance ratio (i.e., the drug mass leaving the perfusate divided by the drug mass appearing in the plasma).

High-performance liquid chromatographic analysis of trilostane and ketotrilostane in rat plasma.

A simple high-performance liquid chromatographic (HPLC) method for assaying trilostane, a synthetic steroid, and one of its metabolites, ketotrilostane, in small volumes of rat plasma has been developed. A single liquid-liquid extraction was used to isolate the two compounds from acidified plasma prior to the quantitative analysis. The HPLC conditions involved the use of a Spherisorb ODS column (250 mm x 4.6 mm I.D.) and a mobile phase of 1,4-dioxan-Sorenson's buffer at pH 5.0 (52:48, v/v). Ethisterone was used as an internal standard. Trilostane and ketotrilostane were detected by their ultraviolet absorbance at 255 nm. Recoveries greater than 80% and detection limits of 50 ng/ml were obtained for both compounds. Inter-day coefficients of variation were less than 10%.

Microparticles as potentially orally active immunological adjuvants.

A model microparticulate carrier system, capable of partially protecting an entrapped antigen against enzymatic degradation, has been successfully used to induce an enhanced secretory immune response to an incorporated model soluble antigen following oral administration to experimental rats. Ovalbumin was incorporated into polyacrylamide microparticles (2.55 microns diameter) and administered orally on four consecutive days to rats primed 14 days earlier by intraperitoneal injection. The memory secretory IgA antibody response (day 65) to the microparticle incorporated antigen group was significantly raised relative to a soluble antigen control group response (p less than 0.01), following administration of a booster dose of soluble antigen to both groups (day 61).

The effect of Miglycol 812 oil on the oral absorption of propranolol in the rat.

This work has examined the effect of Miglyol 812 oil and its composite fatty acids on the oral absorption of propranolol with reference to its intravenous (i.v.) pharmacokinetics. Propranolol hydrochloride, spiked with 4-(3) H labelled compound, was administered i.v. or orally to male Wistar rats and blood concentrations of parent material determined by liquid scintillation counting after extraction into toluene. An i.v. dose-linearity study indicated dose-independent pharmacokinetics for propranolol at 1-2 mg kg-1, with a mean Cls, Vss, MRTi.v. and t0.5 beta of 0.076 L min-1 kg-1, 4.74 L kg-1, 57.81 min and 47.10 min, respectively. At 5 mg kg-1, there was evidence of non-linearity with MRTi.v. increased by about 250%, Vss by 170% and t0.5 beta by 230% compared with the lower doses. After oral administration of propranolol (10 mg kg-1) in aqueous solution, with or without Tween 80 (6%), the mean absorption time (MAT) and terminal half-life were approximately 55 min and 86 min, respectively. The MAT for propranolol administered in a 50% octanoic and lauric acid (1:1 by weight) oil-in-water emulsion, stabilized with 6% Tween 80 (129-90 min), was significantly longer compared with that for a 50% Miglyol 812 oil-in-water emulsion containing the same surfactant (16.55 min). The terminal half-life of propranolol administered in the fatty acid formulation (128.96 min), unlike that for the Miglyol emulsion (54-37 min), was significantly longer compared with that observed after i.v. administration (t0.5 beta = 47 min).(ABSTRACT TRUNCATED AT 250 WORDS)