Chronic liver injury in rats and humans upregulates the novel enzyme angiotensin converting enzyme 2.

BACKGROUND: Angiotensin converting enzyme (ACE) 2 is a recently identified homologue of ACE that may counterregulate the actions of angiotensin (Ang) II by facilitating its breakdown to Ang 1-7. The renin-angiotensin system (RAS) has been implicated in the pathogenesis of cirrhosis but the role of ACE2 in liver disease is not known. AIMS: This study examined the effects of liver injury on ACE2 expression and activity in experimental hepatic fibrosis and human cirrhosis, and the effects of Ang 1-7 on vascular tone in cirrhotic rat aorta. METHODS: In sham operated and bile duct ligated (BDL) rats, quantitative reverse transcriptase-polymerase chain reaction was used to assess hepatic ACE2 mRNA, and western blotting and immunohistochemistry to quantify and localise ACE2 protein. ACE2 activity was quantified by quenched fluorescent substrate assay. Similar studies were performed in normal human liver and in hepatitis C cirrhosis. RESULTS: ACE2 mRNA was detectable at low levels in rat liver and increased following BDL (363-fold; p < 0.01). ACE2 protein increased after BDL (23.5-fold; p < 0.05) as did ACE2 activity (fourfold; p < 0.05). In human cirrhotic liver, gene (>30-fold), protein expression (97-fold), and activity of ACE2 (2.4 fold) were increased compared with controls (all p < 0.01). In healthy livers, ACE2 was confined to endothelial cells, occasional bile ducts, and perivenular hepatocytes but in both BDL and human cirrhosis there was widespread parenchymal expression of ACE2 protein. Exposure of cultured human hepatocytes to hypoxia led to increased ACE2 expression. In preconstricted rat aorta, Ang 1-7 alone did not affect vascular tone but it significantly enhanced acetylcholine mediated vasodilatation in cirrhotic vessels. CONCLUSIONS: ACE2 expression is significantly increased in liver injury in both humans and rat, possibly in response to increasing hepatocellular hypoxia, and may modulate RAS activity in cirrhosis.

Effect of angiotensin II type 1 receptor blockade on experimental hepatic fibrogenesis.

BACKGROUND/AIMS: The aim of this study was to investigate whether in the liver, as in other tissues, there is evidence that angiotensin II, acting via the angiotensin II type 1 receptor (AT1-R), plays a role in fibrogenesis. METHODS: Sprague-Dawley rats were divided into three groups; sham, bile duct ligated (BDL) and BDL + AT1-R antagonist, irbesartan. Real time RT-PCR was utilised to assess gene expression of the AT1 receptor, TGF-beta1 and alpha1 (I) collagen in the liver. TGF-beta1 and alpha1 (I) collagen mRNA expression and localisation were also assessed by in situ hybridisation. TGF-beta1 activity was assessed by using the TGF-beta inducible gene product betaig-h3. Fibrosis was assessed by the Knodell scoring system, tissue hydroxyproline content and picro-sirius red staining. RESULTS: Real time RT-PCR revealed that there was a 6-fold up-regulation in AT1 receptor expression in BDL animals compared with shams. This was associated with marked increases in TGF-beta1, betaig-h3 and alpha1 (I) collagen gene expression which were attenuated by AT1-RA treatment. However, AT1-RA therapy produced no significant change in liver histology or hydroxyproline content. CONCLUSIONS: These results suggest that in the liver angiotensin II may play an important role in the fibrogenic response to injury. However, whether treatment with an AT1-RA will be of therapeutic benefit remains to be determined.

Cefonicid 'restores' the depressed activities of polymorphonuclear cells from chronic haemodialysis patients and renal transplant recipients in vitro.

BACKGROUND: Chronic haemodialysis patients and renal transplant recipients are highly susceptible to infection characterized by high morbidity and mortality and related to an impairment of the phagocytic response. SUBJECTS AND METHODS: In order to elucidate how cefonicid, a cephalosporin with a broad spectrum of activity and once-daily dosage, influences this phagocytic response, the effects of the drug upon the functions of human PMNs from both healthy individuals and immunocompromised patients were investigated. RESULTS: In vitro, PMNs from haemodialysed patients and renal transplant recipients showed a diminished phagocytic efficiency with reduced phagocytosis and bactericidal activity towards intracellular Klebsiella pneumoniae when compared with that seen in PMNs from healthy subjects. Cefonicid significantly affected the activity of PMNs from healthy volunteers, resulting in either an increased percentage of ingested klebsiellae or a reduced intracellular bacterial load when compared with the control, drug-free system. When cefonicid was added to PMNs from uraemic patients a pattern similar to that observed with phagocytes from healthy subjects was detected: the antibiotic was able to 'restore' the depressed primary functions of PMNs, resulting in a significant increase in both phagocytosis and killing activity. CONCLUSIONS: Cefonicid, with its several immunoproperties observed in this study, possesses interesting beneficial properties which make it suitable for the treatment of infections in patients with impaired components of the immune system.

Enhanced effects of amoxycillin/clavulanic acid compared with amoxycillin and clavulanic acid alone on the susceptibility to immunodefenses of a penicillin-resistant strain of Streptococcus pneumoniae.

The recent increase in the incidence of infections due to Streptococcus pneumoniae resistant to penicillin and other antibiotics, often associated with considerable morbidity and mortality, has been recognized as an alarming problem. From the recent medical literature data it emerges that among beta-lactam antibiotics used as an empiric treatment for infections caused by S. pneumoniae, amoxycillin and amoxycillin/clavulanic acid are the most active oral antibiotics and may be considered as a first-line therapeutic agent for the treatment of these infections. Since the therapeutic result of the treatment of an infection is determined by the combined effect of the antimicrobials and host defenses, we investigated the effect of amoxycillin, with and without clavulanic acid, upon the in vitro interaction between human polymorphonuclear leukocytes (PMNs) and a penicillin-resistant strain of S. pneumoniae. Amoxycillin significantly inhibited the streptococcal uptake by PMNs referred to the control system. Clavulanic acid did not have any significant effect upon the interaction PMNs-S. pneumoniae. The addition of amoxycillin/clavulanic acid to phagocytes and streptococci resulted in a synergystic potentiation of the activity of both drugs upon the PMN functions towards S. pneumoniae in such a manner that the bacteria became more susceptible to either the phagocytosis or the microbicidal activities of phagocytes. These effects came in addition to the intrinsic, excellent antimicrobial properties of this drug combination. Although the clinical significance of the observed enhanced effects of amoxycillin/clavulanate are far from elucidated, the possibility exists that they may play a contributory role, especially in patients with impaired host defense.

[Treatment of Community Acquired Pneumonia (CAP) in adults with amoxicillin/clavulanic acid switch therapy: a multicenter italian study] / Trattamento della polmonite acquisita in comunita' nell'adulto, dopo fallimento dl terapia antibiotica orale domiciliare, con amoxicillina/acido clavulanico switch therapy. Esperienza italiana.

Patients with community acquired pneumonia (CAP) previously treated with other oral antibiotics (Cephalosporins 35,3%, Macrolides 26,9%, Tetracyclines 14,1%, Quinolones 12,8%, other 10,9%) for at least 72 hours at home were considered for this national multicentre study. 43 hospitalized patients (17 males and 26 females) ranging between the ages of 19 and 79 were treated with Amoxicillin/Clavulanic acid (AMC) 1,2 g e.v., T.l.D. for at least 3 days. I.V. Treatments were switched to AMC p.o. after apyrexial status. Average treatment duration was 10,8 + 3.6. Sputum/B.A.L. samples were obtained from all patients submitted for microbiological exams in order to determine microbiological aetiology of CAP in patients who have failed on previous antibiotics. At the end of treatment, 30 patients (96,8%) were considered cured, while treatment failed in 1 patient (3,2%). 12 patients were considered not evaluable because serology was positive for M.pneumoniae (5 pts); for C.pneumoniae (3 pts.); 1 patients was positive for Mycobacterium tuberculosis; 1 patient was positive for HIV and Mycobacterium spp.; 2 patients were non-evaluable for lung or bronchial tumor. Not reported adverse events.

Potential effects of amoxycillin/clavulanic acid and ticarcillin/clavulanic acid on human granulocyte activity: a comparative study.

The efficacy of an antimicrobial agent in the therapy of infection depends upon the interaction of bacteria, antibiotic and phagocytes. The influence of both ticarcillin/clavulanic acid and amoxycillin/clavulanic acid on the phagocytic and bactericidal activity of human PMNs in vitro was investigated. The results show that clavulanic acid, with its beta-lactamase inhibitory properties, potentiated the efficacy of both ticarcillin and amoxycillin, resulting in a significantly increased susceptibility of a beta-lactamase producing strain of Klebsiella pneumoniae to phagocytic and microbicidal activities of human PMNs. Overall, amoxycillin/clavulanic acid showed greater enhancement of the killing of K. pneumoniae by human PMNs.

Ticarcillin/clavulanic acid: determination of minimal inhibitory concentrations against bacterial strains isolated from patients in intensive care units. Comparison with other agents.

A total of 303 bacterial strains isolated from bronchoaspirates of Intensive Care Unit (ICU) patients, collected through June and December 1993, were tested for susceptibility to ticarcillin/clavulanic acid, imipenem, amikacin, ceftazidime, ciprofloxacin and piperacillin. The minimal inhibitory concentration (MIC) for each antibiotic was determined according to the NCCLS, by means of serial dilution on microplates. The isolates, 80.8% of which were beta-lactamase producing strains, belonged to Pseudomonas aeruginosa (79 strains), Pseudomonas fluorescens (8 strains), Xanthomonas maltophila (25 strains), Escherichia coli (16 strains), Klebsiella-Enterobacter-Serratia (KES) (62 strains), Proteus spp. (15 strains), Acinetobacter spp. (22 strains), Moraxella spp. (15 strains), Bacteroides catarrhalis (8 strains), Haemophilus spp. (11 strains), Staphylococcus aureus (32 strains), Enterococcus faecalis (10 strains). The highest rate of susceptibility to ticarcillin/clavulanic acid (100%) was detected among E. faecalis (MIC 2-16 micrograms/ml), B. catarrhalis (MIC 1-4 micrograms/ml) and Haemophilus spp. (MIC 1-4 micrograms/ml). Among the non-fermenting microorganisms ticarcillin/-clavulanic acid showed good activity toward P. aeruginosa and P. fluorescens (86% and 75% respectively). It was also very active against X. maltophilia with a susceptibility of 96%. Susceptibility to the other antibiotics tested was within the range of 16% and 28%.

Potentiation of human polymorphonuclear leukocyte phagocytosis and intracellular bactericidal activity by amoxycillin/clavulanic acid.

The use of broad spectrum beta-lactamase inhibitors in association with beta-lactam agents provides one strategy to overcome the enzymatic resistance. Clavulanic acid is a potent inhibitor of a wide range of bacterial beta-lactamases and its potentiating effect on amoxycillin has been established both in vitro and in clinical trials. Since the efficacy of an antimicrobial agent in the therapy of infections depends on the interaction of bacteria, antibiotic and phagocytes, we investigated the effect of amoxycillin/clavulanic acid on the in vitro interaction between human polymorphonuclear cells (PMNs) and beta-lactamase producing strains of Klebsiella pneumoniae and Staphylococcus aureus. Clavulanic acid did not have any significant influence upon the PMN phagocytosis and killing against intracellular bacteria. Interestingly, the presence of the suicide inhibitor, with its beta-lactamase inhibitory properties, potentiated the activity of amoxycillin against the beta-lactamase producing strains of K. pneumoniae and S. aureus in such a manner that bacteria became significantly more susceptible to either phagocytosis or microbicidal activities of human phagocytes, compared to both the control and amoxycillin systems.

The antibacterial activity of amoxycillin/clavulanic acid against Staphylococcus aureus ingested by human granulocytes.

The effect of amoxycillin, and amoxycillin/clavulanic acid on the in vitro interaction between human polymorphonuclear cells and a beta-lactamase producing strain of Staphylococcus aureus was investigated. Amoxycillin alone, at half the MIC, significantly inhibited the bacterial uptake by polymorphonuclear (PMN) cells compared with the control; as a consequence the killing of intracellular staphylococci was higher. Clavulanic acid did not have any significant effect upon the activities of phagocytes. The combination amoxycillin/clavulanic acid possesses beneficial properties which result in enhancement of both phagocytosis and microbicidal activity of PMN cells against the beta-lactamase producing strain of S. aureus. A synergic effect between drugs and serum activity was noted.

Comparative evaluation of the clinical and microbiological efficacy of co-amoxiclav vs cefixime or ciprofloxacin in bacterial exacerbation of chronic bronchitis.

In an open randomized study 218 outpatients (159 males and 59 females) ranging between 18 and 85 years of age (mean 61.9) suffering from bacterial exacerbation of chronic bronchitis have been randomly treated: 79 with co-amoxiclav (amoxicillin 875 mg+clavulanic acid 125 mg) twice daily, 69 with cefixime (400 mg) once daily, and 70 with ciprofloxacin (500 mg) twice daily for an average period of 10 days. Before treatment start, 234 bacterial strains (105 Gram-positive and 129 Gram-negative) were isolated as the cause of exacerbation; the leading pathogens were Streptococcus pneumoniae and Haemophilus spp. Eradication rates at the end of treatment were 82.2% for the co-amoxiclav group, 77.6% for the cefixime group, and 81.2% for ciprofloxacin group. Clinical success (cure+improvement) was obtained in 90.8% of the cases treated with co-amoxiclav, in 80.9% for the cefixime group and in 85.7% of patients treated with ciprofloxacin. Seven adverse events (8.9%) of which 4 cases of diarrhea and 3 of itching, were recorded in the co-amoxiclav group. Eleven adverse events (14.7%) were recorded in the cefixime group including gastrointestinal disturbances in 6 patients and mild to moderate increase of liver function in 2. Nine adverse events (12.9%) occurred in the ciprofloxacin group, including insomnia in 3 patients, gastrointestinal disturbances in 2, and serious increase of liver function tests in one patient. It can be concluded that there were no statistically significant differences among the three treatment groups. However, co-amoxiclav demonstrated a higher efficacy rate than cefixime and ciprofloxacin and was better tolerated. Therefore, it can be used as a first-choice drug in the treatment of exacerbation of chronic bronchitis.

Efficacy and tolerability of azithromycin versus amoxicillin/clavulanic acid in acute purulent exacerbation of chronic bronchitis.

An open randomized trial was conducted in 142 hospitalized and out-patients with acute purulent exacerbation of chronic bronchitis to compare the clinical efficacy and tolerability of azithromycin (n = 69) and amoxicillin/clavulanic acid (n = 73). Azithromycin (500 mg) was administered as a single dose for three days and amoxicillin/clavulanic acid (amoxicillin 875 mg-clavulanic acid 125 mg) was given b.i.d. for 8 days (8.16 +/- 1.18). Before therapy and 24-48 hours after the end of treatment, sputum culture (by positioning five orthodontal swabs at the opening of salivary gland ducts after a washing of the oral cavity with sterile saline solution to avoid oral contamination), chest X-rays, arterial blood gas analysis, trials of respiratory functions and routine blood tests were performed. In the azithromycin group (69 patients) the efficacy rate was 67.6% (46 patients: 34 cured and 12 improved); in 22 patients (32.4%) the treatment failed; 1 patient was not evaluated because of no follow-up. The overall efficacy rate in the amoxicillin/clavulanic acid group (73 patients) was 97.3% (71 patients: 60 cured and 11 improved); in 1 patient (1.4%) the treatment failed and 1 patient was a drop-out for side effects. All pathogens isolated before treatment were susceptible to the antibiotics administered. At the end of treatment microbiological efficacy was 67.1% in the azithromycin group and 98.6% in the amoxicillin/clavulanic acid group. The tolerability was judged good in both treatment groups. Side effects were observed in 1 patient treated with amoxicillin/clavulanic acid (diarrhea), which imposed interruption of treatment, and in 2 patients from the azithromycin group (gastralgia and biochemical laboratory tests: renal function).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ticarcillin and ticarcillin/clavulanic acid on the in-vitro activity of human granulocytes against beta-lactamase-producing Klebsiella pneumoniae.

Clavulanic acid is an effective inhibitor of a broad range of clinically important beta-lactamases and its combination with some beta-lactam antibiotics such as ticarcillin has been shown to extend the inhibition spectrum of the beta-lactams. The activity of ticarcillin, both alone and in combination with clavulanic acid, upon PMN phagocytosis and bactericidal activity towards Klebsiella pneumoniae was investigated. The results indicate that a combination of ticarcillin with clavulanic acid is more active than ticarcillin alone against a beta-lactamase-producing strain of K. pneumoniae, and hence may significantly increase the bacterial vulnerability to phagocyte functions.

Effect of rufloxacin upon non-specific immune defences: in-vitro, ex-vivo and in-vivo results.

This study investigated in-vitro, ex-vivo and in-vivo the immunomodulatory effects of rufloxacin. 0.5 MIC of rufloxacin significantly enhanced human macrophage phagocytosis and increased intracellular killing of Klebsiella pneumoniae in vitro. Pre-incubation of K. pneumoniae with rufloxacin made the bacteria more susceptible to both phagocytosis and intracellular killing by human macrophages than control organisms. Following pre-exposure of macrophages to 0.5 MIC of rufloxacin, there was a significant increase in the intracellular killing of K. pneumoniae compared with the controls, indicating the ability of rufloxacin to cross biological membranes and to remain active within phagocytes. Ex-vivo experiments show that iv administration of rufloxacin in mice lead to an increase in both phagocytic and microbicidal intracellular activity by phagocytes. In-vivo models of experimental infections showed that prophylactic administration of rufloxacin increased the survival of mice after challenge with Candida albicans.

Serum digoxin levels after concomitant ticarcillin and clavulanic acid administration.

Recently it has been recognized that steady-state serum digoxin concentrations may increase or fall to ineffective levels when the glycoside is administered together with several antibiotics. Our study was designed to assess if serum digoxin levels may be modified by the concomitant use of a ticarcillin and clavulanic acid. The study was carried out in 15 hospitalized patients suffering from exacerbation of their chronic bronchitis without liver disease and renal failure. Serum digoxin levels were not significantly modified by the concomitant use of a ticarcillin and clavulanic acid, although peak digoxin serum concentrations were slightly lower. However, the average time to achieve the maximum concentration and area under the curve over 24 h did not change.

Clinical pharmacokinetics of theophylline during co-treatment with ticarcillin plus clavulanic acid in patients suffering from acute exacerbation of chronic bronchitis.

The effect of ticarcillin/clavulanic acid, taken for 7 days as vials containing 1000 mg of ticarcillin and 200 mg of clavulanic acid twice daily intramuscularly, on the steady-state pharmacokinetics of theophylline was studied in 12 patients suffering from acute exacerbation of chronic obstructive pulmonary disease. Initially, patients were treated for four days with theophylline as sustained-release formulation in the amount of 600 mg daily; on the last day, blood samples were taken for theophylline determination. Theophylline concentrations were measured serially for 12 hours by the method of polarized immunofluorescence (Abbott TDx system). Subsequently, while theophylline was continued at the same dosage, each patient received in addition ticarcillin/clavulanic acid vials every 12 hours. After seven days of this combined medication, the serial assays of plasma were repeated at the same time intervals as before. No influence of ticarcillin/clavulanic acid was detectable on the steady-state theophylline pharmacokinetics. It is concluded that both drugs can be administered concomitantly without any dosage adjustment of theophylline.

Effects of cefonicid on platelet aggregation.

Beta-lactam antibiotics may interfere with platelet aggregation by inhibiting the binding of agonists of platelet aggregation, such as ADP and collagen, to specific receptor sites. The aim of this study was to evaluate in vitro the effects of cefonicid, a semi-synthetic cephalosporin, on platelet aggregation. Spontaneous platelet aggregation and platelet aggregation induced by ADP and collagen were assessed. Platelets from healthy subjects were incubated with cefonicid at final concentrations of 0.1 mg/ml, 1 mg/ml and 10 mg/ml (0.1 mg/ml is the concentration of cefonicid achieved in humans at therapeutic doses). When compared with saline, cefonicid at a concentration of 0.1 mg/ml had no effect on platelet aggregation, but at 1 mg/ml it inhibited ADP-induced aggregation and at 10 mg/ml it also inhibited aggregation induced by collagen. These findings suggest that therapeutic doses of cefonicid do not affect platelet aggregation.

Therapeutic efficacy and renal effects of cefonicid in the treatment of difficult urinary tract infections.

UNLABELLED: EFFICACY, renal effects and nephrotoxicity of the cephalosporin cefonicid (CEF) were evaluated in 11 adult patients with urinary tract infection and varying renal function (creatinine cl 19-161 ml/min, mean 75). CEF was administered i.m. for 7 days at a daily dose adjusted to renal function of the patients. EFFICACY: At the 4th day and at the end of the treatment urine cultures were negative in all cases; a recurrence of the infection was observed in 4 patients 10 days after completion of therapy. Renal effects and nephrotoxicity: CEF neither modified plasma creatinine, urea, uric acid and their renal clearances nor glomerular filtration rate. Only the urinary enzyme activity of alanine aminopeptidase increased slightly at the end of the therapy. It returned to basal values in the post-treatment period. Urinary enzyme activities of gamma-glutamyltransferase, alkaline phosphatase, N-acetyl-beta-D-glucosaminidase and lysozyme were unmodified during and after treatment with CEF. These results indicate that CEF is an effective antimicrobial agent which does not influence renal function, nor cause nephrotoxic effects.

Penetration of cefonicid into human lung tissue and lymph nodes.

The present study was undertaken in order to investigate the penetration of cefonicid, a long-acting parenteral cephalosporin, with enhanced activity against most gram-positive and gram-negative pathogens, into human lung tissue and lymph nodes in patients undergoing open thoracotomy. Samples of lung tissue, lymph nodes and serum were obtained at various times after a single intramuscular dose of 1 g. The concentration of cefonicid was assayed by an agar diffusion method with Bacillus subtilis used as the test organism. The mean concentrations of cefonicid in serum at 2, 4, 8, 12 and 24 h after the injection were 91.5, 66.1, 35.7, 21.8 and 2.9 micrograms/ml, respectively. The mean levels of cefonicid into the hilar lymph nodes at the same times were 22.3, 18.7, 12.0, 6.9 and 1.5 micrograms/ml, respectively, while its concentrations in lung tissue were lower than those in lung lymph nodes up to the 12th hour (12.1, 14.6, 7.8, 5.4 and 1.9 micrograms/ml, respectively). Our results show that cefonicid was well distributed in interstitial fluid from which pulmonary lymph is formed and that its concentrations in lung tissue and lymph nodes were sufficient to inhibit most pathogens involved in respiratory tract infections. This finding was considered important, because it demonstrated that the high binding by plasma protein of cefonicid did not prevent it from entering lung tissue and fluids in useful quantities.