Cellular mechanisms by which proinsulin C-peptide prevents insulin-induced neointima formation in human saphenous vein.

AIMS/HYPOTHESIS: Endothelial cells (ECs) and smooth muscle cells (SMCs) play key roles in the development of intimal hyperplasia in saphenous vein (SV) bypass grafts. In diabetic patients, insulin administration controls hyperglycaemia but cardiovascular complications remain. Insulin is synthesised as a pro-peptide, from which C-peptide is cleaved and released into the circulation with insulin; exogenous insulin lacks C-peptide. Here we investigate modulation of human SV neointima formation and SV-EC and SV-SMC function by insulin and C-peptide. METHODS: Effects of insulin and C-peptide on neointima formation (organ cultures), EC and SMC proliferation (cell counting), EC migration (scratch wound), SMC migration (Boyden chamber) and signalling (immunoblotting) were examined. A real-time RT-PCR array identified insulin-responsive genes, and results were confirmed by real-time RT-PCR. Targeted gene silencing (siRNA) was used to assess functional relevance. RESULTS: Insulin (100 nmol/l) augmented SV neointimal thickening (70% increase, 14 days), SMC proliferation (55% increase, 7 days) and migration (150% increase, 6 h); effects were abrogated by 10 nmol/l C-peptide. C-peptide did not affect insulin-induced Akt or extracellular signal-regulated kinase signalling (15 min), but array data and gene silencing implicated sterol regulatory element binding transcription factor 1 (SREBF1). Insulin (1-100 nmol/l) did not modify EC proliferation or migration, whereas 10 nmol/l C-peptide stimulated EC proliferation by 40% (5 days). CONCLUSIONS/INTERPRETATION: Our data support a causative role for insulin in human SV neointima formation with a novel counter-regulatory effect of proinsulin C-peptide. Thus, C-peptide can limit the detrimental effects of insulin on SMC function. Co-supplementing insulin therapy with C-peptide could improve therapy in insulin-treated patients.

Estudio toxicológico y teratogénico del extracto metanólico de cinnamomun zeylanicum (canela) / Toxicológico and teratogénico study of the metanólico extract of cinnamomun zeylanicum (cinnamon)

Se realizó el estudio fitoquímico, toxicológico agudo y citotóxico del cinnamomum zeylanicum (canela). Para la determinación de la DL50 se utilizaron 30 ratones albinos, cuyos pesos oscilaron entre 25 y 30 gr., siguiendo el método de Probits. Igualmente se determinó la concentración letal media (CL-50) en artemia salina. La actividad citotóxica y teratogénica fue evaluada en huevos de Tetrapygus Níger (erizo de mar). Nos permite concluir, siguiendo los criterios de William, que el extracto metanólico de la canela es ligeramente tóxico y posee efecto citotóxico frente al erizo de mar, no evidenciándose efecto teratogénico, a las dosis empleadas.

We have performed a Phytochemic. Toxicologic and Cytotoxic study, of Cinamomum zeylanicum (canela) in laboratory. We have determinated the letal 50-doses (DLSO) in mice, the letal middle concentration (CL_50) in Artemia salina and the cytotoxic and teratogenic effect on Tetrapygus niger eggs (sea Hedgehog). We may conclude following the William Criterions that the metanolic extract of canela is lightly toxic and it has cytotoxic effects on sea Hedgehog at the doses studied.

Experimental studies of sewer exfiltration.

The effects of joint openings and in-pipe sediment on exfiltration losses in an experimental sewer are reported and the influence of flow and head on loss rates are also evaluated. Exfiltration rates tend to be exponential with changes in head for clean-water tests but exhibit power functions when the pipe is subject to sedimentation. In-pipe sediment leads to an effective sealing of joints especially if the invert deposits are both organic in nature and contain saturated adhesive material such as shredded toilet tissue. Simple tracer techniques are described to quantify exfiltration losses and the potential effects of tracer adsorption by pipe solids are evaluated.

Pharmacodynamics of moxifloxacin, levofloxacin and sparfloxacin against Streptococcus pneumoniae.

An in vitro pharmacokinetic model (IVPM) was used to simulate the human serum pharmacokinetics of moxifloxacin, levofloxacin and sparfloxacin, and to compare their pharmacodynamics against Streptococcus pneumoniae exhibiting a wide range of susceptibilities to fluoroquinolones. Logarithmic-phase cultures were exposed to peak concentrations achieved in human serum of moxifloxacin, levofloxacin or sparfloxacin with oral doses of 400, 500 and 200 mg, respectively. Human elimination pharmacokinetics were simulated, and viable bacterial counts were measured at 0, 1, 2, 4, 6, 8, 24 and 36 h. Moxifloxacin was rapidly bactericidal (>3 logs of killing) against all 10 S. pneumoniae strains, with 99.9% kills of eight strains occurring within 1-3 h after dosing. Maximum kills ranged from 5 to >6 logs. Moxifloxacin eradicated seven strains from the IVPM within 8 h of the first dose, and eradicated two other strains within 24 h. Although levofloxacin and sparfloxacin were also bactericidal against all 10 S. pneumoniae strains, the rates of killing were somewhat slower, with sparfloxacin exhibiting the slowest rate of kill. In summary, moxifloxacin's increased anti-pneumococcal potency compared with levofloxacin and its more favourable pharmacokinetics compared with sparfloxacin provided enhanced pharmacodynamic activity against some S. pneumoniae strains when maximum doses were simulated in an IVPM.

Pharmacodynamics of moxifloxacin and levofloxacin against Staphylococcus aureus and Staphylococcus epidermidis in an in vitro pharmacodynamic model.

An in vitro pharmacokinetic model was used to compare the pharmacodynamics of moxifloxacin and levofloxacin against 3 Staphylococcus aureus and 3 Staphylococcus epidermidis strains. Logarithmic-phase cultures were inoculated into the peripheral compartment of hollow-fiber cartridges and exposed to the peak serum concentrations achieved in humans with oral doses of moxifloxacin (400 mg) and levofloxacin (500 mg). Drugs were added at 0 and 24 h, elimination kinetics were simulated, and changes in viable bacterial counts were evaluated over the course of 36 h. Moxifloxacin was bactericidal against all 6 staphylococci (times to 99.9% kill, 1-3 h). Against most strains, bacterial killing continued through 36 h, with total kills exceeding 5.5 logs. Levofloxacin was bactericidal against 5 of the strains, with similar times to 99.9% kill. In contrast to moxifloxacin, however, resistant subpopulations emerged in 4 strains during therapy with levofloxacin, and this could have important implications for treatment of staphylococcal infections. These in vitro observations warrant the clinical evaluation of moxifloxacin in the treatment of staphylococcal infections.

Beta-lactamase inhibitor combinations with extended-spectrum penicillins: factors influencing antibacterial activity against enterobacteriaceae and Pseudomonas aeruginosa.

Production of beta-lactamases is the most common mechanism by which gram-negative bacteria express resistance to beta-lactam antibiotics. One successful method of circumventing the threat of plasmid-encoded beta-lactamases is to combine inhibitors of these enzymes with a penicillin. Currently, four inhibitor-penicillin combinations are in clinical use: ampicillin-sulbactam, amoxicillin-clavulanate, ticarcillin-clavulanate, and piperacillin-tazobactam. Of these, ticarcillin-clavulanate and piperacillin-tazobactam have the broadest spectra of activity that includes Pseudomonas aeruginosa. Many factors influence the activity and pharmacodynamics of these combinations, including potency of both agents, pharmacokinetics of the inhibitor, type and quantity of beta-lactamase produced by the target bacterium, and potential for the inhibitor to induce expression of chromosomal cephalosporinases in the target bacterium. Although ticarcillin-clavulanate and piperacillin-tazobactam have similar spectra of activity, they have many differences. Most notable are increased potency of piperacillin against Enterobacteriaceae and P aeruginosa, increased activity of piperacillin-tazobactam against gram-negative pathogens producing penicillin-sensitive enzyme (PSE)-class beta-lactamase or hyperproducing other plasmid-encoded beta-lactamases, and the more favorable pharmacokinetics of tazobactam. In the treatment of P. aeruginosa infections, the potential for clavulanate to induce expression of chromosomal cephalosporinase and antagonize antibacterial activity of ticarcillin is a concern, especially in patients who lack protective host defenses. These are not concerns with piperacillin-tazobactam.

Emerging resistance problems among respiratory tract pathogens.

The number-1 indication for antibiotic prescriptions in the United States is a respiratory tract infection. The changing spectrum of pathogens and emerging bacterial resistance are changing the way these infections are managed. The epidemiology of community-acquired pneumonia has changed significantly in the past 20 years, with increased diversity of pathogens and mortality. Emerging resistance in respiratory tract pathogens, particularly to beta-lactams, is an increasing concern. Of the important gram-negative pathogens, more than a third of Haemophilus influenzae isolates are now resistant to beta-lactam antibiotics, as well as virtually all isolates of Moraxella catarrhalis. Of the gram-positive organisms, more than 40% of Streptococcus pneumoniae isolates are no longer susceptible to penicillin, and methicillin resistance has been reported in up to half of Staphylococcus aureus isolates in some institutions. Among staphylococci, resistance to the beta-lactam methicillin is often accompanied by resistance to multiple classes of antibiotics, particularly the macrolides. Little resistance to fluoroquinolones has been reported among gram-negative respiratory tract pathogens and S pneumoniae, although increasing resistance may be seen as these drugs are used with increasing frequency. In contrast, fluoroquinolone resistance can develop rapidly in S aureus and appears to be associated with methicillin resistance. Fortunately, many of the newer fluoroquinolones appear to offer significant activity against methicillin-resistant S aureus isolates and are active against ciprofloxacin-resistant strains of S pneumoniae. Today, to combat respiratory tract infections, a broad-based empiric therapy needs to be used and bacterial resistance must be taken into account. New antimicrobial options must be considered, with an emphasis on effective drug use and optimal dosing. Even if a direct relationship between antibiotic resistance and clinical outcomes in the treatment of pneumonia in adults has not been extensively demonstrated, the increasing problem of resistance has changed treatment approaches for respiratory tract infections as a whole.

Inhaled steroids for neonatal chronic lung disease.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a chronic disorder associated with prematurity. Systemic steroids induce at least a temporary improvement in respiratory function, but are associated with adverse side effects. Inhaled steroids have fewer side effects. OBJECTIVES: To determine if inhaled corticosteroids are effective in alleviating the morbidity of bronchopulmonary dysplasia (BPD) compared to 0-placebo. SEARCH STRATEGY: We identified randomised, controlled trials (RCT) within the Cochrane Database, references from retrieved trials, hand searches of journals and contact with pharmaceutical companies and experts in this field. SELECTION CRITERIA: Only randomised controlled trials involving infants with chronic lung disease of prematurity and treated with inhaled steroids versus placebo were included. Patients receiving systemic corticosteroids were excluded. Co-interventions included antenatal systemic steroids, routine neonatal intensive care, ventilatory support, surfactant replacement therapy, diuretics and bronchodilators. DATA COLLECTION AND ANALYSIS: Four of the seven included trials were of good methodological quality. There were five parallel-group trials in ventilated infants. These were comparable in terms of population, co-interventions and need for increased inspired oxygen concentration. They differed in terms of type, dose and duration (7-28 days) of inhaled steroids. Two cross-over trials were performed in non-ventilated patients. MAIN RESULTS: The inability to extubate during treatment was markedly reduced in infants treated with inhaled steroids; Peto Odds Ratio (OR) 0.12, 95% Confidence Interval (CI) 0.03 to 0.43. There was heterogeneity in this finding, however, with one study that contributed 30% of the total number of patients reporting no successful extubations in either treatment arm over one week. The risk of sepsis appeared similar between the two groups (N=3, OR=0.72, 95%CI: 0.21 to 2.43). The small number of trials precluded analysis to examine the effect of differences in drug, duration of therapy, delivery system, co-interventions, and disease severity. Reduced oxygen requirements were reported in one of the two trials performed in non-ventilated infants, but inadequate data reporting precluded pooling of data. REVIEWER'S CONCLUSIONS: In ventilated infants with BPD, inhaled steroids administered for 1 to 4 weeks improved the rate of extubation with no apparent increase in the risk of sepsis. No firm conclusion could be derived with regard to the efficacy of inhaled steroids in non-ventilated infants.

A taxonomy for developing cultural competence.

This paper proposes a taxonomy to develop culturally competent practitioners. Arguments about what this might mean and how this could be achieved are discussed first, identifying problems with multicultural and antiracist approaches. The model follows the cognitive, emotional and behavioural levels of Steinaker and Bell's experiential taxonomy. Five elements are proposed: cultural awareness, cultural knowledge, cultural understanding, cultural sensitivity and cultural competence. These could address, in increasingly sophisticated and increasingly praxis-oriented ways, issues of power and the construction of meanings and identities which go beyond essentialist notions of ethnicity.

Crying significantly reduces absorption of aerosolised drug in infants.

AIM: Therapeutic aerosols are routinely used in the management of infant obstructive airways disease. Infants often become distressed during administration. The aim of this study was to determine the influence of distress and disease severity on the absorption of aerosolised drug in this age group. METHODS: Fifteen infants, eight with resolving chronic lung disease of prematurity (mean age, 13 months), and seven infants with normal birth histories (mean age, 11 months) were studied. Flow through small airways was assessed by measurement of partial forced expiratory flow volume curves. Each infant was then given a dose of 20 mg nebulised sodium cromoglicate via a Sidestream nebuliser and distress was graded as: 1, not distressed; 2, distressed. Infants were excluded if contact with the mask was lost for more than 10 seconds. Urine was collected for eight hours and analysed for excreted drug by radioimmunoassay. RESULTS: Sodium cromoglicate is absorbed by the respiratory epithelium, and undergoes renal (43%) and hepatic (57%) excretion. A mean of 0.43% of the total nebulised drug dose was excreted in the urine of the non-distressed infants compared with 0.11% of total dose in the distressed infants. Flow through the small airways was significantly reduced in infants with chronic lung disease of prematurity. Maximum flow at functional residual capacity did not correlate with the amount of drug in the urine, but the degree of distress did. CONCLUSION: To maximise absorption, nebulised drugs should be given to settled infants. The degree of airways disease does not influence drug absorption in this age group.

Pharmacodynamics of levofloxacin and ciprofloxacin against Streptococcus pneumoniae.

An in-vitro pharmacokinetic model was used to compare the pharmacodynamics of levofloxacin and ciprofloxacin against four penicillin-susceptible and four penicillin-resistant Streptococcus pneumoniae. Logarithmic-phase cultures were exposed to the peak concentrations of levofloxacin or ciprofloxacin observed in human serum after 500 mg and 750 mg oral doses, human elimination pharmacokinetics were simulated, and viable bacterial counts were measured at 0, 1, 2, 4, 6, 8, 12, 24 and 36 h. Levofloxacin was rapidly and significantly bactericidal against all eight strains evaluated, with eradication of six strains occurring despite area under the inhibitory curve over 24 h (AUIC24) values of only 32-64 SIT(-1) x h (serum inhibitory titre over time). The pharmacodynamics of ciprofloxacin were more variable and the rate of bacterial killing was consistently slower than observed with levofloxacin. Ciprofloxacin eradicated five strains despite having an AUIC24 of only 44 SIT(-1) x h. These data suggest that the increased potency of levofloxacin and more favourable pharmacokinetics compared with ciprofloxacin provide enhanced pharmacodynamic activity against S. pneumoniae. Furthermore, these data suggest that the minimum AUIC required for clinical efficacy against and eradication of S. pneumoniae with levofloxacin and ciprofloxacin may be well below the 125 SIT(-1) x h identified by other studies.

Pharmacodynamics of trovafloxacin, ofloxacin, and ciprofloxacin against Streptococcus pneumoniae in an in vitro pharmacokinetic model.

An in vitro pharmacokinetic model was used to simulate the pharmacokinetics of trovafloxacin, ofloxacin, and ciprofloxacin in human serum and to compare their pharmacodynamics against eight Streptococcus pneumoniae strains. The MICs of ofloxacin and ciprofloxacin ranged from 1 to 2 micrograms/ml. Trovafloxacin was 8- to 32-fold more potent, with MICs of 0.06 to 0.12 microgram/ml. Logarithmic-phase cultures were exposed to peak concentrations of trovafloxacin, ofloxacin, or ciprofloxacin achieved in human serum after 200-, 400-, and 750-mg oral doses, respectively. Trovafloxacin was dosed at 0 and 24 h, and ofloxacin and ciprofloxacin were dosed at 0, 12, and 24 h. Human elimination pharmacokinetics were simulated, and viable bacterial counts were measured at 0, 2, 4, 6, 8, 12, 24, and 36 h. Trovafloxacin was rapidly and significantly bactericidal against all eight strains evaluated, with viable bacterial counts decreasing at least 5 logs to undetectable levels. Times to 99.9% killing were only 1 to 3 h. Although the rate of killing with ofloxacin was substantially slower than that with trovafloxacin, ofloxacin was also able to eradicate all eight strains from the model, despite a simulated area under the inhibitory curve/MIC ratio (AUC/MIC) of only 49. In contrast, ciprofloxacin eradicated only five strains (AUC/MIC = 44) from the model. Against the other three strains (AUC/MIC = 22), the antibacterial activity of ciprofloxacin was substantially diminished. These data corroborate clinical data and suggest that trovafloxacin has a pharmacodynamic advantage over ciprofloxacin and ofloxacin against S. pneumoniae in relation to its enhanced antipneumococcal activity.

Clavulanate induces expression of the Pseudomonas aeruginosa AmpC cephalosporinase at physiologically relevant concentrations and antagonizes the antibacterial activity of ticarcillin.

Although previous studies have indicated that clavulanate may induce AmpC expression in isolates of Pseudomonas aeruginosa, the impact of this inducer activity on the antibacterial activity of ticarcillin at clinically relevant concentrations has not been investigated. Therefore, a study was designed to determine if the inducer activity of clavulanate was associated with in vitro antagonism of ticarcillin at pharmacokinetically relevant concentrations. By the disk approximation methodology, clavulanate induction of AmpC expression was observed with 8 of 10 clinical isolates of P. aeruginosa. Quantitative studies demonstrated a significant induction of AmpC when clavulanate-inducible strains were exposed to the peak concentrations of clavulanate achieved in human serum with the 3.2- and 3.1-g doses of ticarcillin-clavulanate. In studies with three clavulanate-inducible strains in an in vitro pharmacodynamic model, antagonism of the bactericidal effect of ticarcillin was observed in some tests with regimens simulating a 3.1-g dose of ticarcillin-clavulanate and in all tests with regimens simulating a 3.2-g dose of ticarcillin-clavulanate. No antagonism was observed in studies with two clavulanate-noninducible strains. In contrast to clavulanate. No antagonism was observed in studies with two clavulanate-noninducible strains. In contrast to clavulanate, tazobactam failed to induce AmpC expression in any strains, and the pharmacodynamics of piperacillin-tazobactam were somewhat enhanced over those of piperacillin alone against all strains studied. Overall, the data collected from the pharmacodynamic model suggested that induction per se was not always associated with reduced killing but that a certain minimal level of induction by clavulanate was required before antagonism of the antibacterial activity of its companion drug occurred. Nevertheless, since clinically relevant concentrations of clavulanate can antagonize the bactericidal activity of ticarcillin, the combination of ticarcillin-clavulanate should be avoided when selecting an antipseudomonal beta-lactam for the treatment of P. aeruginosa infections, particularly in immunocompromised patients. For piperacillin-tazobactam, induction is not an issue in the context of treating this pathogen.

Cefepime-aztreonam: a unique double beta-lactam combination for Pseudomonas aeruginosa.

An in vitro pharmacokinetic model was used to determine if aztreonam could enhance the pharmacodynamics of cefepime or ceftazidime against an isogenic panel of Pseudomonas aeruginosa 164, including wild-type (WT), partially derepressed (PD), and fully derepressed (FD) phenotypes. Logarithmic-phase cultures were exposed to peak concentrations achieved in serum with 1- or 2-g intravenous doses, elimination pharmacokinetics were simulated, and viable bacterial counts were measured over three 8-h dosing intervals. In studies with cefepime and cefepime-aztreonam against the PD strain, samples were also filter sterilized, assayed for active cefepime, and assayed for nitrocefin hydrolysis activity before and after overnight dialysis. Against WT strains, the cefepime-aztreonam combination was the most active regimen, but viable counts at 24 h were only 1 log below those in cefepime-treated cultures. Against PD and FD strains, the antibacterial activity of cefepime-aztreonam was significantly enhanced over that of each drug alone, with 3.5 logs of killing by 24 h. Hydrolysis and bioassay studies demonstrated that aztreonam was inhibiting the extracellular cephalosporinase that had accumulated and was thus protecting cefepime in the extracellular environment. In contrast to cefepime-aztreonam, the pharmacodynamics of ceftazidime-aztreonam were not enhanced over those of aztreonam alone. Further pharmacodynamic studies with five other P. aeruginosa strains producing increased levels of cephalosporinase demonstrated that the enhanced pharmacodynamics of cefepime-aztreonam were not unique to the isogenic panel. The results of these studies demonstrate that aztreonam can enhance the antibacterial activity of cefepime against derepressed mutants of P. aeruginosa producing increased levels of cephalosporinase. This positive interaction appears to be due in part to the ability of aztreonam to protect cefepime from extracellular cephalosporinase inactivation. Clinical evaluation of this combination is warranted.

Rationale behind high-dose amoxicillin therapy for acute otitis media due to penicillin-nonsusceptible pneumococci: support from in vitro pharmacodynamic studies.

To evaluate whether increased doses of amoxicillin should be used to treat acute pneumococcal otitis media, an in vitro pharmacokinetic model was used to evaluate the killing of pneumococci by amoxicillin when middle ear pharmacokinetics were simulated. Logarithmic-phase cultures were exposed to peak concentrations of 3, 6, and 9 microg of amoxicillin per ml every 12 h, and an elimination half-life of 1.6 h was simulated. Changes in viable bacterial counts were measured over 36 h. All three doses rapidly decreased the viable bacterial counts of penicillin-susceptible strains below the 10-CFU/ml limit of detection by 6 to 10 h and maintained counts below this limit through 36 h. The 3-microg/ml peak dose was much less effective against two of three strains with intermediate penicillin resistance and all three penicillin-resistant strains, with bacterial counts approaching those in drug-free control cultures by 12 h. The 6-microg/ml peak dose completely eliminated two of three strains with intermediate penicillin resistance and maintained viable counts of the other nonsusceptible strains at 1.5 to 2 logs below the initial inoculum through 36 h. The 9-microg/ml peak dose was most effective, completely eliminating all three strains with intermediate penicillin resistance and maintaining the viable counts of the resistant strains at 3 to 4 logs below the original inoculum. The pharmacodynamics observed in this study suggest that peak concentrations of amoxicillin of 6 to 9 microg/ml may be sufficient for the elimination of penicillin-nonsusceptible pneumococcal strains causing otitis media, especially those with intermediate resistance to amoxicillin. In vivo pharmacokinetic studies are needed to determine if these levels can be achieved in middle ear fluid with amoxicillin at 70 to 90 mg/kg/day divided into two daily doses. If these levels are reliably achieved, then clinical studies are warranted.