Methylglyoxal affects cognitive behaviour and modulates RAGE and Presenilin-1 expression in hippocampus of aged mice.

Methylglyoxal (MG), a potent glycotoxin that can be found in the diet, is one of the main precursors of Advanced glycation end products (AGEs). It is well known that modifications in lifestyle such as nutritional interventions can be of great value for preventing brain deterioration. This study aimed to evaluate in vivo how an oral MG treatment, that mimics a high MG dietary intake, could affect brain health. From our results, we demonstrated that MG administration affected working memory, and induced neuroinflammation and oxidative stress by modulating the Receptor for Advanced glycation end products (RAGE). The gene and protein expressions of RAGE were increased in the hippocampus of MG mice, an area where the activity of glyoxalase 1, one of the main enzymes involved in MG detoxification, was found reduced. Furthermore, at hippocampus level, MG mice showed increased expression of proinflammatory cytokines and increased activities of NADPH oxidase and catalase. MG administration also increased the gene and protein expressions of Presenilin-1, a subunit of the gamma-secretase protein complex linked to Alzheimer's disease. These findings suggest that high MG oral intake induces alteration directly in the brain and might establish an environment predisposing to AD-like pathological conditions.

GH-releasing peptides and bone.

It has been extensively demonstrated that GH secretagogues (GHS) play a role in the regulation of bone metabolism in animals and humans. Unlike GH, administration of GHS does not increase bone resorption markers, suggesting that a mechanism exclusively linked to GH release cannot account for the effect of these compounds. On this line, we investigated the effect of GHS and ghrelin, the endogenous ligand of GHS receptors, on bone cells. We found that both hexarelin and ghrelin significantly stimulated cell proliferation and increased alkaline phosphatase and osteocalcin production in primary cultures of rat calvaria osteoblasts. In the same cells, we were able to detect the mRNA for the GHS receptor by RT-PCR and the corresponding protein by Western blot, indicating that ghrelin and GHS may bind and activate this receptor. Two isoforms of GHS receptors (GHS-R), which are presumably the result of alternate processing of pre-mRNA, have been identified and designed receptors 1a (R1a) and 1b (R1b). Ghrelin, the endogenous ligand of the GHS receptors, binds with high affinity GHS-R1a only. Unlike fetal calvaria cells, osteoblasts derived from adult rat tibia did not express the GHS-R1 a, but only the biologically inactive isoform GHS-R1b. The latter isoform was present in only one of the three specimens of human osteoblasts obtained from the iliac crest or the upper femur of patients during surgery. These results would indicate that only osteoblasts from fetal bone express functional receptors responsive to ghrelin and GHS.

Serum osteoprotegerin and receptor activator of nuclear factors kB (RANKL) concentrations in normal children and in children with pubertal precocity, Turner's syndrome and rheumatoid arthritis.

BACKGROUND: Osteoprotegerin (OPG) is a secreted member of the TNF receptor superfamily. OPG is made by osteoblastic cells and is expressed in a wide variety of cell and tissue types. It acts as a decoy receptor by binding the receptor activator of nuclear factors kB (RANKL) and preventing RANKL-induced osteoclast formation and differentiation. Numerous cytokines and hormones (TGF-beta, PTH, vitamin D, glucocorticoids and oestrogens) exert their effects on osteoclastogenesis by regulating the production of OPG. PATIENTS AND METHODS: In the present study we compared serum OPG and RANKL concentrations in a group of normal children (1-14 years old) with those of pair-aged children affected by different diseases [Turner's syndrome (TS), early/precocious puberty (PP) and rheumatoid arthritis (RA)]. OPG and RANKL concentrations were measured by an enzyme immunoassay method using a commercial kit. RESULTS: Mean (+/- SD) OPG level in normal children was 4.05 +/- 1.63 pmol/l with no difference between males and females. OPG values in children 1-4 years old (5.87 +/- 2.22 pmol/l) were significantly higher than in children 4-14 years old (3.55 +/- 0.97 pmol/l). OPG levels in children with RA were significantly higher than in controls (6.33 +/- 2.57 pmol/l vs. 4.05 +/- 1.63 pmol/l, P < 0.01); patients with TS or PP had OPG levels superimposable to those of controls (2.61 +/- 0.67 pmol/l and 3.99 +/- 0.85 pmol/l, respectively), but in TS OPG levels were significantly lower than in age-matched females. Mean RANKL concentration in normal subjects was 0.81 +/- 1.55 pmol/l; there was a slight decline in RANKL levels with age. RANKL concentrations in subjects with TS, PP, RA and controls did not differ significantly, and did not differ from those published in adult normal subjects. CONCLUSIONS: It appears from our data that OPG serum levels in healthy children aged > 4 years are similar to those present in young adult men, with higher levels in the first 4 years of life. Although the meaning of the alterations of OPG levels observed in pathological conditions is still obscure, they appear potentially interesting in view of a key role played by this protein in bone homeostasis.

Phagocytosis and killing of Candida albicans of polymorphonuclear cells in patients with organ transplant of periodontal disease.

BACKGROUND: The easiest defence system carried out by the organism, the inflammatory response, happens with the support of phagocyting cells: the polymorphonuclear leukocytes (PMNL) or neutrophils are the most important cell line acting as the first defence of the organism against bacterial agents. Previous studies have shown a correlation between a reduction of the immune function and development of periodontal disease. Furthermore, it is well known that transplant patients show a variety of oral lesions as a consequence of their therapy, in particular to immunosuppressive drugs. The aim of this study is to evaluate the phagocytosis and killing functions of PMNL in transplant patients and in patients with periodontal disease in comparison with a group of healthy subjects. METHODS: PMNL, were isolated by spontaneous sedimentation from heparinized blood and centrifugation of plasma on density medium. Phagocytosis rate was expressed as the percentage of Candida albicans phagocyted after 20' incubation and phagocyting PMNLs. Intracellular killing was expressed as the percentage of yeast cells killed. RESULTS: We did not find a significant decrease of phagocytosis in transplant patients and patients with periodontal disease while these two groups of patients showed a decrease of PMNL killing activity in respect to healthy controls, an effect which was unrelated to the severity of periodontal disease. CONCLUSIONS: These results suggest that a reduction of killing activity, either spontaneous or drug-induced, would contribute to the development of periodontal disease.

Effect of antibiotics on Bordetella pertussis adhering activity: hypothesis regarding mechanism of action.

Microbial adherence to epithelial cell surfaces has been implicated as the first step in the initiation of several infectious diseases. The ability of antibiotics to affect the properties of bacterial adherence to cell surfaces may be a criterion in selecting antibiotics for therapy. This study was performed in order to investigate the activity of amoxicillin, chloramphenicol, and clarithromycin in modifying the adhering activity of Bordetella pertussis to human epithelial cells. The actions of antibiotics, alone or combined with aprotinin, were compared with that of trypsin, aprotinin and trypsin+aprotinin, to investigate the chemical nature of the ligand where antibiotics could act. The adhering activity was evaluated on human epithelial cells, collected from the oral mucosa, challenged with B. pertussis A2963 previously incubated in the presence of the tested substances for 1 h at 37 degrees C in a shaker incubator. After staining, the percentage of mucosal cells with more than 50 adhering bacteria was evaluated. Under the described experimental conditions, trypsin significantly reduced the adherence of B. pertussis. Aprotinin had no effect but was able to counteract the inhibitory action of trypsin. Both clarithromycin and chloramphenicol markedly reduced adhering activity and their actions were not counteracted by aprotinin. Amoxicillin was without effect. It was hypothesized that chloramphenicol and clarithromycin, exerting their antimicrobial action by inhibiting bacterial protein synthesis, affected bacterial adhesion through an unknown mechanism without proteolytic effect.

Brodimoprim concentrations in bronchial mucosa, bronchial secretions and middle ear effusions.

Brodimoprim, a structural analogue of trimethoprim, is a long acting broad spectrum antibacterial agent characterized by a good pharmacokinetic profile, allowing once daily (OD) administration. The aim of this study was to investigate the penetration of brodimoprim into bronchial mucosa, bronchial secretion and middle ear effusion, in order to evaluate the efficacy of the antibiotic in respiratory tract infections. The study was performed in patients affected by chronic bronchitis having to undergo diagnostic bronchoscopy (n = 26), in patients affected by exacerbation of chronic bronchitis with purulent or mucopurulent secretions (n = 10), and in patients affected by otitis media with eardrum perforation (n = 28). Patients were orally treated with 400 mg of brodimoprim (single dose). Samples of serum, bronchial mucosa, bronchial secretion and middle ear effusion were collected in the separate series of patients above mentioned, at different times after drug administration. Brodimoprim determinations were performed by a microbiological method using Bacillus subtilis ATCC 6633 as test microorganism. Brodimoprim reached the highest concentration in serum 4 h after administration and was still detectable at 24th hour. In bronchial mucosa and in bronchial secretion the peaks were reached at 8th hour (9.7 +/- 5.3 mg/kg and 4.57 +/- 1 mg/l respectively) while in middle car effusion were reached at 4th hour (4.8 +/- 2.5 mg/l). The drug was still detectable at antibacterial concentrations, both in infected fluids and in tissue samples, 24 hours after administration (4.3 +/- 1.8 mg/kg in bronchial mucosa; 3.5 +/- 0.66 mg/l in bronchial secretions; 3 +/- 0.6 mg/l in middle ear effusion).(ABSTRACT TRUNCATED AT 250 WORDS)

The diffusion of clarithromycin and roxithromycin into nasal mucosa, tonsil and lung in humans.

The diffusion of clarithromycin and roxithromycin into respiratory tract tissues was studied in 174 adult patients undergoing surgery. Patients received clarithromycin 250 mg orally (500 mg in the case of lung tissue), or roxithromycin 150 mg orally, both given every 12 h, for three days with the last dose administered at different times before surgery. Clarithromycin reached peak tissue levels 4 h after administration and achieved mean peak concentrations of 8.32 mg/kg +/- 2.57 in nasal mucosa, 6.47 mg/kg +/- 2.8 in tonsil, and 17.47 mg/kg +/- 3.29 in lung tissue. Roxithromycin reached peak tissue levels between 4 and 6 h after administration, achieving mean peak concentrations of 1.78 mg/kg +/- 0.73 in nasal mucosa, 2.2 mg/kg +/- 1.21 in tonsil, and 2.14 mg/kg +/- 0.87 in lung tissue. Clarithromycin and roxithromycin demonstrated contrasting pharmacokinetic behaviour. Roxithromycin was characterized by high concentrations in serum and low concentrations in tissues. Clarithromycin on the other hand, is characterized by therapeutic serum concentrations and high tissue concentrations.

Cytosolic androgen receptors in the neuroendocrine tissues of the golden hamster: influence of photoperiod and melatonin treatment.

Hamsters exposed for eight weeks to short photoperiod (LD 10:14) or treated with melatonin in the late afternoon under long photoperiod (LD 14:10) had significantly higher number of cytosolic androgen receptors in the pituitaries, hypothalami and harderian glands, as compared to the long photoperiod (LD 14:10) exposed controls. The numerical value of the apparent Kd was two to three times lower in the hypothalami and pituitaries, but not in the harderian glands of the animals from these groups. These results indicate that alterations in receptor numbers and affinity constants may be responsible for the dramatic changes in the sensitivity of the hypothalamo-pituitary axis to the negative feedback actions of the gonadal steroids, observed under inhibitory photoperiods and that this effect could be duplicated by late afternoon melatonin treatment.