DIBI, a polymeric hydroxypyridinone iron chelator, reduces ocular inflammation in local and systemic endotoxin-induced uveitis.

BACKGROUND/OBJECTIVE: Non-infectious uveitis is an inflammatory disease of the eye commonly treated by corticosteroids, though important side effects may result. A main mediator of inflammation are oxygen free radicals generated in iron-dependent pathways. As such, we investigated the efficacy of a novel iron chelator, DIBI, as an anti-inflammatory agent in local and systemic models of endotoxin induced uveitis (EIU). METHODS: Firstly, the effects of DIBI in systemic EIU in Lewis rats were established. 2 hours post intravenous LPS or LPS/DIBI injections, leukocyte activation and functional capillary density (FCD) were examined using intravital microscopy (IVM) of the iridial microcirculation. Secondly, the toxicity of DIBI was evaluated in BALB/C mice for both acute and chronic dosages through gross ocular examination, intraocular pressure measurements and hematoxylin-eosin staining of ocular tissue. Lastly, three groups of BALB/C mice, control, LPS or DIBI + LPS, were studied to evaluate the effectiveness of DIBI in treating local EIU. Five hours post-local intravitreal (i.v) injection, leukocyte activation and capillary density were examined via IVM. RESULTS: Treatment of systemic EIU with DIBI resulted in a reduction of leukocyte activation and FCD improvement within the iridial microcirculation. Toxicity studies suggested that acute and chronic DIBI administration had no adverse effects in the eye. In the local EIU model, DIBI was shown to reduce leukocyte activation and restored the FCD/DCD ratio, providing evidence for its anti-inflammatory properties. CONCLUSIONS: Our study has provided evidence that DIBI has anti-inflammatory effects in experimental uveitis. Additionally, no local ocular toxicity was observed.

The utility of iron chelators in the management of inflammatory disorders.

Since iron can contribute to detrimental radical generating processes through the Fenton and Haber-Weiss reactions, it seems to be a reasonable approach to modulate iron-related pathways in inflammation. In the human organism a counterregulatory reduction in iron availability is observed during inflammatory diseases. Under pathological conditions with reduced or increased baseline iron levels different consequences regarding protection or susceptibility to inflammation have to be considered. Given the role of iron in development of inflammatory diseases, pharmaceutical agents targeting this pathway promise to improve the clinical outcome. The objective of this review is to highlight the mechanisms of iron regulation and iron chelation, and to demonstrate the potential impact of this strategy in the management of several acute and chronic inflammatory diseases, including cancer.

Leukocyte-endothelial interactions within the ocular microcirculation in inflammation and infection.

Leukocyte-endothelial interactions within the microvasculature represent a hallmark of inflammation regardless of whether the inflammation results from non-infectious or infectious triggers. In this review, we highlight features of leukocyte recruitment in ocular disease and postulate mechanisms by which the infiltrating cells may lead to the progression of the ocular inflammatory response, including cytokine and chemokine production, T cell or non-T cell responses. Additionally, ex-vivo and in vivo methods used to study the general features of the immune response are discussed, with a specific focus on intravital imaging, which allows real-time non-invasive examination of leukocyte-endothelial interactions in the ocular microvasculature. At the present time there are still significant gaps in our understanding of the process of leukocyte recruitment in vivo in different microvascular beds. Further studies using non-invasive imaging approaches, such as intravital microscopy, provide an opportunity to study dynamic tissue-specific leukocyte-endothelial interactions in vivo and identify novel targets for early intervention in the inflammatory process. This knowledge is essential to the rational use of therapeutics to resolve inflammation in ocular disease.

Acute administration of antibiotics modulates intestinal capillary perfusion and leukocyte adherence during experimental sepsis.

Antibiotic treatment represents a mainstay of therapy for clinical sepsis. Distinct from their antimicrobial effects, antibiotics may impact the inflammatory process in sepsis, e.g. within the intestinal microcirculation. The impact of seven antibiotics relevant to clinical sepsis on intestinal leukocyte recruitment and capillary perfusion was studied in rats with colon ascendens stent peritonitis (CASP)-induced sepsis or after endotoxin [lipopolysaccharide (LPS)] challenge. The following antibiotics were included: daptomycin; erythromycin; imipenem; linezolid; tigecycline; tobramycin; and vancomycin. The number of rolling and adherent leukocytes in intestinal submucosal venules and the functional capillary density (FCD) in three layers of the intestinal wall were assessed using intravital microscopy. CASP-induced sepsis reduces the intestinal FCD by 30-50%. Single administration of daptomycin, tigecycline or linezolid increased the intestinal FCD. CASP sepsis increased the number of rolling leukocytes by 4.5-fold, which was reduced by erythromycin but increased by vancomycin. The number of adherent leukocytes increased 3-fold in rats with CASP sepsis. It was reduced following administration of daptomycin, tigecycline (in V1 and V3 venules), erythromycin and linezolid (in V1 venules). However, following tobramycin and vancomycin, leukocyte adhesion was further enhanced. Administration of tigecycline and linezolid reduced the LPS-induced increase in the number of adherent leukocytes by 50%. However, imipenem did not affect leukocyte adherence. In conclusion, this work highlights the beneficial impact of the antibiotics daptomycin, tigecycline, erythromycin and linezolid in that they improve intestinal capillary perfusion and/or reduce leukocyte recruitment, whilst the antibiotics imipenem, tobramycin and vancomycin do not exert these properties.

Impact of antibiotics on the microcirculation in local and systemic inflammation.

The main function of antibiotics is related to their capacity to eliminate a microorganism. In addition to the antimicrobial function of antibiotics, they are known to have anti-inflammatory and vasomodulatory effects on the microcirculation. The ability of non-antimicrobial derivatives of antibiotics to control inflammation illustrates the distinct anti-microbial and anti-inflammatory roles of antibiotics. In this review, we discuss the impact of antibiotics on leukocyte recruitment and the state of the microcirculation. Literature reporting the effect of antibiotics in non-infectious inflammatory conditions is reviewed as well as the studies demonstrating the anti-inflammatory effects of antibiotics in animal models of infection. In addition, the effect of the antibiotics on the immune system is summarized in this review, in order to postulate some mechanisms of action for the proand anti-inflammatory contribution of antibiotics. Literature reported the effect of antibiotics on the production of cytokines, chemotaxis and recruitment of leukocytes, production of reactive oxygen species, process of phagocytosis and autophagy, and apoptosis of leukocytes. Yet, all antibiotics may not necessarily exert an anti-inflammatory effect on the microcirculation. Thus, we suggest a model for spectrum of anti-inflammatory and vasomodulatory effects of antibiotics in the microcirculation of animals in local and systemic inflammation. Although the literature suggests the ability of antibiotics to modulate leukocyte recruitment and microperfusion, the process and the mechanism of action are not fully characterized. Studying this process will expand the knowledge base that is required for the selection of antibiotic treatment based on its anti-inflammatory functions, which might be particularly important for critically ill patients.

Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study.

BACKGROUND: Herbal remedies used by patients for treatment of inflammatory bowel disease include slippery elm, fenugreek, devil's claw, Mexican yam, tormentil and wei tong ning, a traditional Chinese medicine. Reactive oxygen metabolites produced by inflamed colonic mucosa may be pathogenic. Aminosalicylates (5-ASA) are antioxidant and other such agents could be therapeutic. AIMS: To assess the antioxidant effects of herbal remedies in cell-free oxidant-generating systems and inflamed human colorectal biopsies. METHODS: Luminol-enhanced chemiluminescence in a xanthine/xanthine oxidase cell-free system was used to detect superoxide scavenging by herbs and 5-ASA, and fluorimetry to define peroxyl radical scavenging using a phycoerythrin degradation assay. Chemiluminescence was used to detect herbal effects on generation of oxygen radicals by mucosal biopsies from patients with active ulcerative colitis. RESULTS: Like 5-ASA, all herbs, except fenugreek, scavenged superoxide dose-dependently. All materials tested scavenged peroxyl dose-dependently. Oxygen radical release from biopsies was reduced after incubation in all herbs except Mexican yam, and by 5-ASA. CONCLUSIONS: All six herbal remedies have antioxidant effects. Fenugreek is not a superoxide scavenger, while Mexican yam did not inhibit radical generation by inflamed biopsies. Slippery elm, fenugreek, devil's claw, tormentil and wei tong ning merit formal evaluation as novel therapies in inflammatory bowel disease.

Pyrrolnitrin from Burkholderia cepacia: antibiotic activity against fungi and novel activities against streptomycetes.

A bacterial strain identified as Burkholderia cepacia NB-1 was isolated from water ponds in the botanical garden in Tübingen, Germany, and was found to produce a broad spectrum phenylpyrrole antimicrobial substance active against filamentous fungi, yeasts and Gram-positive bacteria. In batch culture containing glycerol and L-glutamic acid, the isolate NB-1 produced the antibiotic optimally late in the growth phase and accumulated a main portion in their cells. Isolation and purification of the antibiotic from Burkholderia (Pseudomonas) cepacia NB-1 by acetone extraction, gel filtration on Sephadex LH-20 and preparative HPLC yielded 0.54 mg l-1 of a pure substance. Spectroscopic data (HPLC, MS and NMR) confirmed that the compound was pyrrolnitrin [3-chloro-4-(2'-nitro-3'-chloro-phenyl) pyrrole]. Pyrrolnitrin has an inhibitory effect on the electron transport system, as demonstrated by isolated mitochondria from Neurospora crassa 74 A. This inhibition was relieved by N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride (TMPD), indicating that pyrrolnitrin blocked the electron transfer between the dehydrogenases and the cytochrome components of the respiratory chain. Among Gram-positive bacteria, pyrrolnitrin was most active against certain Streptomyces species, especially S. antibioticus, which has not previously been described in the literature. In the presence of pyrrolnitrin, aerial mycelium and spore formation of Strep. antibioticus was suppressed, although growth continued via substrate mycelium. The new findings of inhibition of streptomycetes and their secondary metabolism by pyrrolnitrin may contribute to the fact that Pseudomonas species predominate in soil and compete even with antibiotic-producing Streptomyces.

GH response to provocation and circulating IGF-I and IGF-binding protein-3 concentrations, the IGF-I generation test and clinical response to GH therapy in children with beta-thalassaemia.

The causes of growth retardation of children with thalassaemia major are multifactorial. We studied the GH response to provocation by clonidine and glucagon, measured the circulating concentrations of insulin, IGF-I, IGF-binding protein-3 (IGFBP-3) and ferritin, and evaluated IGF-I generation after a single dose of GH (0.1 mg/kg per dose) in 15 prepubertal patients with thalassaemia, 15 age-matched children with constitutional short stature (CSS) (height standard deviation score less than -2, with normal GH response to provocation) and 11 children with isolated GH deficiency (GHD). Children with thalassaemia had significantly lower peak GH response to provocation by clonidine and glucagon (6.2 +/- 2.3 and 6.8 +/- 2.1 microg/l respectively) than the CSS group (18.6 +/- 2.7 and 16.7 +/- 3.7 microg/l respectively). They had significantly decreased circulating concentrations of IGF-I and IGFBP-3 (47.5 +/- 19 ng/ml and 1.2 +/- 0.27 mg/l respectively) compared with those with CSS (153 +/- 42 ng/ml and 2.06 +/- 0.37 mg/l respectively), but the IGF-I and IGFBP-3 concentrations were not different from those with GHD (56 +/- 25 ng/ml and 1.1 +/- 0.32 mg/l respectively). These data demonstrate that the GH-IGF-I-IGFBP-3 axis in thalassaemic children is defective. Serum ferritin concentration correlated significantly with GH peak response to provocation (r = -0.36, P < 0.05) and circulating IGF-I (r = -0.47, P < 0.01) and IGFBP-3 (r = -0.42, P < 0.01) concentrations. In the IGF-I generation test, after GH injection, the thalassaemic children had significantly lower IGF-I and IGFBP-3 levels 86.7 +/- 11.2 ng/ml and 2.05 +/- 0.51 mg/l respectively) than those in the CSS group (226 +/- 45.4 ng/ml and 2.8 +/- 0.43 mg/l respectively). The IGF-I response was significantly higher in children with GHD (158 +/- 50 ng/ml) than in thalassaemic children. Six short (height standard deviation score less than -2) thalassaemic children who had defective GH response to provocation (< 10 microg/l), all the children with GHD and eight short normal children (CSS) were treated for 1 year with human GH (18 units/m2 per week divided into daily s.c. doses). After 1 year of GH therapy there was a marked acceleration of growth velocity in both thalassaemic children (from 3.8 +/- 0.6 cm/year to 7.2 +/- 0.8 cm/year) and controls. However, the linear acceleration of growth velocity on GH therapy was significantly slower in thalassaemic children (3.3 +/- 0.3 cm/year increment) compared with those with CSS (5.3 +/- 0.4 cm/year increment) and GHD (6.9 +/- 1.2 cm/year increment) (P < 0.05). Their circulating IGF-I concentration (105 +/- 36 ng/ml) was significantly lower than those for CSS (246 +/- 58 ng/ml) and GHD (189 +/- 52 ng/ml) after 1 year of GH therapy. These data prove that some children with beta-thalassaemia major have a defective GH-IGF-I-IGFBP-3 axis and suggest the presence of partial resistance to GH.

Bone mineral density in prepubertal children with beta-thalassemia: correlation with growth and hormonal data.

Patients with beta-thalassemia major (beta-thalassemia) frequently have bone disorders of multifactorial etiology. We attempted to analyze the relationship between the bone mineral density ([BMD] measured by dual-photon absorptiometry) and auxanologic parameters, degree of siderosis, function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein-3 (IGFBP3) axis, calcium-phosphate balance, parathyroid hormone (PTH), and cytokines (interleukin-1beta [IL-1] and tumor necrosis factor-alpha [TNF-alpha]) in 30 prepubertal children with beta-thalassemia major and 15 age-matched children with constitutional short stature (CSS), who have normal glucose tolerance and thyroid function. Children with beta-thalassemia had a significantly decreased BMD and mean BMD% for age and sex (0.75+/-0.24 g/cm2 and 71%+/-10%, respectively) versus children with CSS (1.06+/-0.3 g/cm2 and 92%+/-7%, respectively). Thalassemic patients had significantly lower circulating concentrations of IGF-I and IGFBP3 (49+/-21 ng/mL and 1.2+/-0.25 mg/L, respectively) compared with control children (153+/-42 ng/mL and 2.1+/-0.37 mg/L, respectively). The GH response to provocation by clonidine and glucagon was defective (peak GH < 7 microg/L) in 12 of the 30 thalassemic children. Serum concentrations of IL-1beta and TNF-alpha did not differ among the two study groups. Hypocalcemia was detected in five of the 30 thalassemic patients: hypoparathyroidism was diagnosed in two of the five and rickets in the other three. BMD was highly correlated with the circulating concentrations of IGF-I and IGFBP3, as well as with the auxanologic parameters (age, weight, height, height standard deviation score [HSDS], and body mass index [BMI]). It is suggested that increasing the circulating IGF-I concentration through aggressive nutritional therapy and/or GH/IGF-I therapy with supplementation with vitamin D and/or calcium might improve bone growth and mineralization and prevent the development of osteoporosis and consequent fractures in these patients. Such therapy requires blinded controlled trials.

Growth hormone secretion and circulating insulin-like growth factor-I (IGF-I) and IGF binding protein-3 concentrations in children with sickle cell disease.

Impaired growth involving both height and weight accompanying sickle cell disease (SCD) poses diagnostic and therapeutic problems. We undertook this study to test the hypothesis that this impaired growth is associated with abnormalities of the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF binding protein-3 (IGFBP-3) axis in 21 children with SCD and that SCD is associated with GH resistance. Nine of 21 children with SCD had a defective GH response to both clonidine and glucagon provocation (peak < 10 micrograms/L); these children differed from the 12 others in having slower linear growth velocity (GV and GVSDS), lower circulating concentrations of IGF-I and IGFBP-3, and either partial or complete empty sellae in computed tomographic scans of the hypothalamic-pituitary area. In this group of patients with SCD, it appears that defective GH secretion and consequent low IGF-I production are the major etiological factors causing the slow growth. The two groups with SCD did not differ significantly in dietary intake, body mass index (BMI), midarm circumferences, skinfold thickness, serum albumin concentration, or intestinal absorption of D-xylose. A single injection of GH produced a smaller increase in circulating IGF-I in children with SCD with or without defective GH secretion versus 10 age-matched children with idiopathic short stature (ISS) and 11 children with isolated GH deficiency (GHD), suggesting partial GH resistance in the SCD group. The presence of defective GH secretion, decreased IGF-I synthesis, and partial resistance to GH in short children with SCD suggests that treatment with IGF-I may be superior to GH therapy for improving growth.

Insulin and glucagon responses to provocation with glucose and arginine in prepubertal children with thalassemia major before and after long-term blood transfusion.

Hypertransfusion therapy has dramatically increased the duration and quality of life in patients with B-thalassemia major; however, it leads to chronic iron overload, and is frequently complicated by the development of diabetes mellitus or impaired glucose tolerance. To determine the early effect of iron overload on the endocrine pancreatic function, we studied glucose, insulin, and glucagon responses to oral load of glucose and to arginine provocation in 15 children with B-thalassemia major, before and after (3.1 +/- 0.6 years) high-transfusion and iron chelation and compared them with 15 age matched normal controls. In addition, we evaluated growth hormone (GH) responses to oral clonidine and measured the circulating insulin-like growth factor-I concentration in thalassemic children on long-term transfusion and controls. After long-term high-transfusion, thalassemic children had significantly decreased serum insulin concentrations and low insulin/glucose ratios at 60 and 120 min after an oral glucose load (1.75 g/kg) in comparison with values before therapy and those for controls. None of the thalassemic children had glucose intolerance after this period of frequent blood transfusion; however, their serum glucose levels at 60 and 120 min after the oral glucose load were significantly higher compared to control children. Thirty minutes after starting arginine infusion, serum insulin concentration was significantly lower in thalassemic children compared to before therapy. Basal and arginine-stimulated glucagon secretions were significantly elevated in thalassemic children on long-term blood transfusion with significantly low serum insulin/glucagon ratios. In addition, the high basal serum glucagon concentrations were not suppressed after the oral glucose load. Despite hyperglucagonaemia in all thalassemic children, their blood glucose dropped appropriately below 50 per cent of the fasting glucose level after an intravenous insulin dose (0.1 U/kg) ruling out any significant insulin-resistance. GH responses to clonidine provocation were subnormal in thalassemic children after long-term blood transfusion compared to controls. In summary, thalassemic children on long-term blood transfusion and iron chelation have progressive and early loss of B-cell mass, manifested by decreased insulin release in response to secretagogues, before the development of significant insulin resistance or impairment of glucose tolerance.

Circulating growth hormone (GH), insulin-like growth factor-I (IGF-I) and free thyroxine, GH response to clonidine provocation and CT scanning of the hypothalamic-pituitary area in children with sickle cell disease.

Serum growth hormone (GH), cortisol, free thyroxine (FT4), thyroid-stimulating hormone (TSH), and insulin like growth factor I (IGF-I) concentrations were measured in 15 children with sickle cell disease (SCD) together with their heights < 5th percentile for age and gender, and in 15 healthy age-matched children who had normal variant short stature (NVSS). GH response to an oral dose of clonidine (0.15 mg/m2) and cortisol response to ACTH stimulation were determined in the two groups. Children with SCD had significantly lower serum concentrations of IGF-I and decreased GH response to stimulation. Eight out of the 15 children with SCD did not mount an appropriate GH response to clonidine provocation (> 10 micrograms/l). CT scanning of the hypothalamic-pituitary area in those eight children with SCD revealed a partial or complete empty sella in all of them. It appears that defective GH release, and consequently low IGF-I production and slow growth velocity in children with SCD might be secondary to hypoxic-vascular insults to their hypothalamic-pituitary axis during one or more of the sickling episodes.

Central nervous system activity of Rhazya stricta (Decne) in mice.

1. The effects of orally administered aqueous lyophilized extract of the leaves of Rhazya stricta (2, 4 & 8 g/kg) on aspects of nervous system function were investigated in mice. 2. In three antinociceptive tests (hot plate, abdominal constriction, and warm water tail flick tests), the extract exhibited dose-dependent and significant antinociceptive activity. Naloxone was ineffective in antagonizing the analgesic effect of Rhazya stricta on tail-flick and abdominal constriction tests, possibly indicating that this effect occurs via non-opiate pathways. 3.Pretreatment of mice with the xenobiotic metabolizing enzymes inhibitor cimetidine (50 mg/kg) did not significantly alter the antinociceptive action of the extract, indicating that the effect is probably due to the parent compound(s) present in the extract and not to metabolites thereof. 4. Rhazya stricta produce dose-dependent sedation, decreased motor activity, and impaired motor control. Time spent on a rotarod treadmill was significantly decreased after treatment with the extract. 5. Rhazya stricta extract (8 g/kg) produced a degree of sedation comparable to that produced by diazepam (5-10 mg/kg), and also significantly increased the reaction time of the tail-flick test, an action which was not produced by diazepam. 6. Administration of R. stricta extract potentiated pentobarbitone sleeping time in a dose dependent manner. The extract did not significantly antagonize picrotoxin induced convulsions. The extract (4 and 8 g/kg) significantly decreased the rectal temperature of normothermic and hyperthermic mice. 7. Pretreatment with R. stricta extract (8 g/kg) completely prevented the occurrence of aggressive behaviour in male mice. 8. It is concluded that the crude extract of R. stricta has central nervous system depressant properties.

Acute urticaria and hepatitis complicating high-dose methotrexate therapy.

We report an unusual case of anaphylaxis and hepatitic dysfunction in a child with the administration of the twenty-third course of high-dose methotrexate. The latter had been used as an adjuvant to prevent pulmonary metastases and the prior 22 courses had been well tolerated. An attempt to reinstate methotrexate after the twenty-third course was again followed by a similar reaction.

[Antigenic response against PPD and antigen 60 in tubercular patients: single antigen versus the combined test]. / Respuesta antigénica frente al PPD y al antígeno 60 en pacientes tuberculosos: antígeno único frente a test combinado.

We analyze serum samples from 70 patients with pulmonary tuberculosis and 50 healthy individuals. The antigenic activity (IgG) against protein purified antigen (PPD) and antigen 60 (A60) from M. tuberculosis. Thirteen patients were also HIV infected, and three patients had AIDS defined by the presence of disseminated tuberculosis. The test using antigen alone showed a 77% sensitivity and 74% specificity when PPD is used. When A60 was used, both values improved (81% sensitivity, 94% specificity). The use of a combined test (PPD and A60) improves the sensitivity (89%) but reduces the specificity (82%). The HIV infected patients showed similar responses to those of other patients. The combined use of different antigens might be useful for diagnosing tuberculosis.

Neurochemical transmission in the dorsal column nuclei.

The transmitter chemistry of the dorsal column nuclei is reviewed, with special emphasis on the monosynaptic component of the dorsal column-medial lemniscal pathway. It is maintained that in this anatomically addressed system concerned mainly with fast, secure sensory transmission, amino acids represent the predominant mechanism used for chemical relay of primary afferent impulses. The major excitatory primary afferent transmitter is most likely glutamic acid, whereas gamma-aminobutyric acid (GABA) fulfills adequately the role of transmitter of recurrent, postsynaptic and presynaptic inhibition. Recent immunohistochemical and physiological evidence indicates that 5-hydroxytryptamine, originating mainly from neurons of the raphé nuclei, plays a modulatory role in dorsal column transmission of innocuous sensory information. The basic synaptic elements involved in transmission across this relay, along with their corresponding chemical identities, are presented in the form of a speculative model.