Selective Clearance of Macrophages in Atherosclerotic Plaques by the Protein Synthesis Inhibitor Cycloheximide

Macrophages are an essential component of unstable atherosclerotic plaques and play a pivotal role in the destabilization process. We have demonstrated previously that local delivery of the mammalian target of rapamycin (mTOR) inhibitor everolimus selectively clears macrophages in rabbit plaques. Because mTOR controls mRNA translation, inhibition of protein synthesis might induce selective macrophage cell death. We therefore investigated in the present study the effect of the protein synthesis inhibitor cycloheximide on macrophage and smooth muscle cell (SMC) viability. In vitro studies with cultured macrophages and SMCs showed that cycloheximide induced selective apoptosis of macrophages in a concentration- and time-dependent manner. Moreover, macrophages could be selectively depleted in rabbit carotid artery rings with collar-induced atherosclerotic plaques after in vitro treatment with cycloheximide. Local in vivo administration of cycloheximide via osmotic minipumps to rabbit carotid arteries with collar-induced atherosclerotic plaques significantly reduced the macrophage but not the SMC content. Cycloheximide-treated plaques showed signs of apoptosis (increased terminal deoxynucleotidyl transferase end labeling and fluorescein isothiocyanate-Val-Ala-dl-Asp(O-methyl)-fluoromethylketone labeling) that did not colocalize with SMCs. Organ chamber studies demonstrated that the functionality of SMCs and the endothelium were not influenced by cycloheximide treatment. All together, these findings demonstrate that cycloheximide decreases the macrophage load in atherosclerotic plaques by induction of apoptosis without changing SMC content or contractility.

[Linezolid: antibacterial activity, clinical efficacy and resistance]

Linezolid is a synthetic antibiotic, the first available agent in a new class of antibiotic called the oxazolidinones, whose particular mechanism of action consists in inhibiting the initiation of protein synthesis. Its spectrum of in vitro and in vivo activity includes staphylococci, streptococci, enterococci, corynebacteria and some anaerobic bacteria (Peptostreptococcus, Clostridium, and Fusobacterium). The first therapeutic results were very encouraging, leading to the marketing of the product in France in 2002. Linezolid is indicated in the treatment of pneumonia and the complicated infections of the skin. Pharmacocinetics studies have shown that linezolid has an excellent bioavailability allowing a fast relay per os. However, failures of treatment under linezolid were reported and resistant strains of staphylococci and enterococci were obtained in vitro and in vivo after therapeutic use of this antibiotic. Changes in the domain V of 23S rRNA were found in the site of fixation, the most frequent was (G out of U) in position 2576 (numbering E. coli). In a context where resistance to traditional treatments in enterococci, pneumococci and S. aureus do not cease to increase, linezolid can be regarded as a therapeutic alternative to treat the infections with Gram-positive cocci.

Drug evaluation: PTC-124--a potential treatment of cystic fibrosis and Duchenne muscular dystrophy

PTC-124, a 1,2,4-oxadiazole compound, is in development by PTC Therapeutics Inc as an orally active small molecule that can override nonsense stop translation signals to produce full-length proteins. PTC-124 is currently being evaluated in phase II clinical trials against cystic fibrosis (CF) and Duchenne muscular dystrophy (DMD). The functional properties of PTC-124 are similar to the aminoglycoside antibiotic gentamicin, but the two compounds are chemically distinct and PTC-124 does not exhibit any antibiotic characteristics. In vitro experiments showed PTC-124 to be superior to gentamicin at ribosomal read-through of nonsense mutations. In vivo investigations revealed that PTC-124 was effective in restoring the production of full-length protein in animal models of CF and DMD. Phase I clinical trials reported that PTC-124 was well tolerated in healthy patients. The author concludes that the encouraging results observed to date make PTC-124 an attractive option for further well-designed, long-term human studies on larger sample populations. The author also predicts that if results continue to be positive, PTC-124 could also be trialed in other single gene disorders with nonsense mutations such as hemophilia, neurofibromatosis, retinitis pigmentosa, bullous skin diseases and lysosomal storage disorders.

RNA therapeutics directed to the non coding regions of APP mRNA, in vivo anti-amyloid efficacy of paroxetine, erythromycin, and N-acetyl cysteine

Lead compounds directed to the 5' leader of the Amyloid Precursor Protein transcript (i.e., paroxetine (SSRI), N-acetyl cysteine (antioxidant), and erythromycin (macrolide antibiotic)) were employed in a pilot study to evaluate their anti-amyloid efficacy in the TgCRND8 transgenic mouse model for Alzheimer's Disease (AD). The relative levels of Abeta peptide were reduced after exposure of mice to paroxetine (N=5), NAC (N=7), and erythromycin (N=7) relative to matched placebo counterparts. Paroxetine limited the levels of APP holoprotein and total Abeta peptide levels (measurements of Abeta were performed at two separate sites by quantitative western blotting and ELISA assay). The paroxetine data provided proof-of-concept for our strategy for further screening the APP 5'UTR target to identify novel drugs that exhibit anti-amyloid efficacy in vivo. Erythromycin and azithromycin were macrolide antibiotics that markedly changed the cleavage of the APP C-Terminal Fragment (CTF) in SH-SY5Y cells. Erythromycin provided orally to TgCRND8 mice consistently (100%) reduced brain Abeta(1-42) levels. These data demonstrated a highly statistically significant anti-amyloid trend for paroxetine, NAC and erythromycin. The potential for conducting further studies with these compounds using larger cohorts of TgCRND8 mice is discussed, particularly since erythromycin has recently been exposed to mice for a further 6 months (N=6). It will be possible to employ the chemical structures of paroxetine and erythromycin as starting points for drug design and development for AD therapeutics.

Halofuginone prevents subglottic stenosis in a canine model

OBJECTIVES

Halofuginone is a low-molecular weight quinazolinone alkaloid coccidiostat that inhibits collagen type I synthesis, extracellular matrix deposition, and angiogenesis. This study was conducted to assess its potential in preventing subglottic stenosis (SGS).

METHODS

We induced SGS in 10 dogs randomly divided into 2 groups. Each group received treatment between 3 days before and 21 days after the induction of SGS. One group received oral halofuginone 40 microg/kg, and the other was given placebo. The area of the subglottic lumen was measured at baseline and 3 months later. In addition, human tracheal fibroblasts were cultured. The inhibitory effect of halofuginone was compared to the effect of mitomycin.

RESULTS

All dogs survived throughout the study with no side effects. Three months after the operation, no halofuginone-treated dog had SGS, in contrast to a 66% to 80% stenosis rate (mean, 72%) in controls (p < .008). Thick fibrotic tissue was found in the placebo-treated larynges, whereas an almost normal architecture was observed in halofuginone-treated larynges. Halofuginone inhibited the growth of human tracheal fibroblasts by 75%, in comparison with 60% inhibition by mitomycin (no statistically significant difference).

CONCLUSIONS

This preliminary study shows that halofuginone is effective in preventing SGS caused by an acute injury. Halofuginone has a potential therapeutic role in preventing SGS in humans.

Therapeutic window for cycloheximide treatment after hypoxic-ischemic brain injury in neonatal rats

We have previously shown that cycloheximide significantly inhibited apoptosis, and reduced ensuing cerebral infarction in a newborn rat model of cerebral hypoxiaischemia. This study was performed to determine the therapeutic window for cycloheximide therapy. Seven day-old newborn rat pups were subjected to 100 min of 8% oxygen following a unilateral carotid artery ligation, and cycloheximide was given at 0, 6, 12 and 24 hr after hypoxia-ischemia (HI). Apoptosis or necrosis was identified by performing flow cytometry with a combination of fluorescinated annexin V and propidium iodide, and the extent of cerebral infarction was evaluated with triphenyl tetrazolium chloride (TTC) at 48 hr and 72 hr after HI, respectively. With cycloheximide treatment at 0 hr after HI, both apoptotic and necrotic cells by flow cytometry were significantly reduced, only necrotic cells were significantly reduced at 6 and 12 hr, and no protective effect was seen if administration was delayed until 24 hr after HI compared to the HI control group. Infarct volume, measured by TTC, was significantly reduced by 92% and 61% when cycloheximide was given at 0 or 6 hr after HI respectively; however, there was an insignificant trend in infarct reduction if cycloheximide was administered 12 hr after HI, and no protective effect was observed when administration was delayed until 24 hr after HI. In summary, cycloheximide was neuroprotective when given within 6 hr after HI in the developing newborn rat brain.

Therapies for the treatment of type 2 diabetes mellitus based on incretin action

Orally ingested glucose leads to a much higher insulin response than intravenous glucose leading to identical postprandial plasma glucose excursions. This phenomenon, termed ''incretin effect'' comprises up to 60% of the postprandial insulin secretion and is diminished in type 2 diabetes. The gastrointestinal hormones glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) promote the incretin effect. Type 2 diabetes is characterized by an incretin defect: while GIP does not stimulate insulin secretion, GLP-1 action is still preserved under supraphysiological concentrations. GLP-1 stimulates insulin secretion only under hyperglycaemic conditions, therefore it does not cause hypoglycaemia. Furthermore, GLP-1 inhibits glucagon secretion and delays gastric emptying. In vitro and animal data demonstrated that GLP-1 increases beta cell mass by stimulating islet cell neogenesis and by inhibiting apoptosis of islets. The improvement of beta cell function can be indirectly observed from the increased insulin secretory capacity of humans receiving GLP-1. In contrast to GIP, GLP-1 may represent an attractive therapeutic method for type 2 diabetes due to its multiple effects also including the simulation of satiety in the central nervous system by acting as transmitter or by crossing the blood brain barrier. Native GLP-1 is degraded rapidly upon intravenous or subcutaneous administration and is therefore not feasible for routine therapy. Long-acting GLP-1 analogs (e.g. Liraglutide) and exendin-4 (Exenatide, Byetta) that are resistant to degradation, called ''incretin mimetics'' are approved (Exenatide, Byetta) or in clinical trials. DPP-4-inhibitors (e.g. Vildagliptin), Sitagliptin and Saxagliptin) that inhibit the enzyme DPP-4 responsible for incretin degradation are also under study.

Linezolid-Induced Inhibition of Mitochondrial Protein Synthesis

BACKGROUND

Linezolid is an oxazolidinone antibiotic that is increasingly used to treat drug-resistant, gram-positive pathogens. The mechanism of action is inhibition of bacterial protein synthesis. Optic and/or peripheral neuropathy and lactic acidosis are reported side effects, but the underlying pathophysiological mechanism has not been unravelled.

METHODS

We studied mitochondrial ultrastructure, mitochondrial respiratory chain enzyme activity, and mitochondrial DNA (mtDNA) in muscle, liver, and kidney samples obtained from a patient who developed optic neuropathy, encephalopathy, skeletal myopathy, lactic acidosis, and renal failure after prolonged use of linezolid. In addition, we evaluated mtDNA, respiratory chain enzyme activity, and protein amount in muscle and liver samples obtained from experimental animals that received linezolid or placebo.

RESULTS

In the patient, mitochondrial respiratory chain enzyme activity was decreased in affected tissues, without ultrastructural mitochondrial abnormalities and without mutations or depletion of mtDNA. In the experimental animals, linezolid induced a dose- and time-dependent decrease of the activity of respiratory chain complexes containing mtDNA-encoded subunits and a decreased amount of protein of these complexes, whereas the amount of mtDNA was normal.

CONCLUSION

These results provide direct evidence that linezolid inhibits mitochondrial protein synthesis with potentially severe clinical consequences. Prolonged courses of linezolid should be avoided if alternative treatment options are available.

Regression of primary low-grade mucosa-associated lymphoid tissue lymphoma of duodenum after long-term treatment with clarithromycin

A 74-year-old woman was referred to our department because of epigastralgia. Endoscopic findings revealed yellowish bumpy mucosa from the bulbus to the second portion of the duodenum. The patient was admitted to our hospital for further examinations and treatment for this lesion. Endoscopic mucosal resection (EMR) was performed on part of the lesion to obtain the final diagnosis, and then mucosa-associated lymphoid tissue (MALT) lymphoma of the duodenum was diagnosed using this procedure. In this case, no evidence of Helicobacter pylori infection in the patient's stomach was detected by any of the diagnostic examinations used, such as the urea breath test, histological study, culture, and serological antibody. For this reason, the patient's duodenal MALT lymphoma was treated solely with long-term clarithromycin, which had an inhibitory action on lymphocyte activation. The lesion showed slight improved during the first 12 days of treatment, and complete regression was reached after 6 months of treatment. It is suggested that the long-term use of clarithromycin may be effective for diseases of the gastrointestinal tract associated with the lymphocyte proliferation.

Third-line rescue therapy with levofloxacin after two H. pylori treatment failures

AIM

Eradication therapy with proton pump inhibitor, clarithromycin and amoxicillin fails in a considerable number of cases. A rescue therapy still fails in more than 20% of the cases. Our aim was to evaluate the efficacy and tolerability of a third-line levofloxacin-based regimen in patients with two consecutive Helicobacter pylori eradication failures.

DESIGN

Prospective multicenter study.

PATIENTS

In whom a first treatment with omeprazole-clarithromycin-amoxicillin and a second with omeprazole-bismuth-tetracycline-metronidazole (or ranitidine bismuth citrate with these antibiotics) had failed.

INTERVENTION

A third eradication regimen with levofloxacin (500 mg b.i.d.), amoxicillin (1 g b.i.d.), and omeprazole (20 mg b.i.d.) was prescribed for 10 days.

OUTCOME

Eradication was confirmed with 13C-urea breath test 4-8 wk after therapy.

RESULTS

One-hundred patients were initially included, and nine were lost for follow-up. All patients but five took all the medications correctly. Per-protocol and intention-to-treat eradication rates were 66% (95% CI = 56-75%) and 60% (50-70%). Adverse effects were reported in 25% of the patients, mainly including metallic taste (8%), nausea (8%), myalgia/arthralgia (5%), and diarrhea (4%); none of them were severe.

CONCLUSION

Levofloxacin-based rescue therapy constitutes an encouraging empirical third-line strategy after multiple previous H. pylori eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole, and tetracycline.

Disseminated Hailey-Hailey disease treated with topical tacrolimus and oral erythromycin: Case report and review of the literature

Hailey-Hailey disease is a rare autosomal dominant skin disorder that typically affects the intertriginous areas. The responsible defect has been identified in the gene named ATP2C1 on chromosome 3q21-24. We present a 50-year-old man with a 16-year history of blistering eruptions and positive familial history where this disease had appeared through four generations. The diagnosis was confirmed by histopathologic studies and negative immunofluorescence findings. A combination of topical tacrolimus therapy and oral erythromycin seemed to play a considerable part in this case, in which all of the lesions healed within 2 weeks.

Effect of Therapeutic Moderate Hypothermia on Multi-drug Resistance Protein 1-Mediated Transepithelial Transport of Drugs

To clarify the effect of therapeutic moderate hypothermia on drug distribution, transepithelial transport via multi-drug resistance protein 1 (MDR1) (also called P-glycoprotein or ABCB1) was evaluated at various temperatures in vitro using LLC-GA5-COL150 cells, which were established by transfecting human MDR1 complementary deoxyribonucleic acid into kidney epithelial LLC-PK(1) cells and express MDR1 on the apical membrane. MDR1 is expressed in the blood-brain barrier to limit drug distribution to the brain by exporting exogenous substances including calcium blockers and antiarrhythmic drugs. Digoxin was used as a typical substrate, as well as the non-substrate tetracycline and paracellular marker inulin. MDR1-mediated transport of digoxin decreased at lower temperatures. Transport of tetracycline also decreased at lower temperatures, probably due to changes in membrane fluidity. However, no change was found at over 32 degrees C, suggesting that passive diffusion does not change during moderate hypothermia. The distribution of MDR1 substrates should be considered during hypothermic conditions, as the clinical outcome could be affected.

[Linezolid, the first oxazolidinone antibiotic]

The spread of multiresistant Staphylococcus and Enterococcus strains required the development of new drugs. Linezolid is the first molecule of a new antibiotic family, oxazolidinones, with an original mechanism of action. In this general review, the authors first present its antibacterial activity, its pharmacokinetic properties, its therapeutic uses in serious Gram-positive infections, pneumonia, skin and soft tissue infections, and also in other indications. They then explain the rules for administration and tolerability.

Prevention of esophageal strictures in a caustic burn model using halofuginone, an inhibitor of collagen type I synthesis

OBJECTIVE

Esophageal strictures caused by caustic injury continue to be a plaguing problem. Halofuginone (HF) has been proven to inhibit the formation of fibrosis in various animal models and human diseases. Its mechanism appears to be through the suppression of the production of collagen alpha1(I) and transforming growth factor-beta signaling pathway. We tried to assess whether HF would have an effect on the formation of strictures after inducing caustic esophageal.

MATERIALS AND METHODS

Esophageal injury was caused by injecting 25% NaOH to an isolated esophageal segment. Study group rats were treated with HF orally for 3 consecutive days before the injury and afterward. Control group rats received regular chow. The results were evaluated by upper gastrointestinal series (UGI) and through pathologic studies.

RESULTS

HF treatment resulted in marked improvement in the esophageal strictures. The UGI series showed esophageal patency of 73% (45%-100%) in the treated animals (n = 7) as compared with almost no patency, 11% (5-16%), in the controls (n = 4) (P = .018). The histologic examination showed significantly less stricture and scarring in the treated group. Whereas the ratio between the esophageal wall thickness to mucosal thickness was 2.34 +/- 0.23 in the study group, the control group had a ratio of 9.56 +/- 0.69 (P = .0044). Finally, whereas 86% of the study group survived, all the rats in the control group died by day 20.

CONCLUSIONS

HF modulated the wound healing reaction caused by caustic injury of the esophagus in a rat model, resulting in increased esophageal patency, reduction in esophageal wall thickness, and increased survival.

Linezolid-induced dyserythropoiesis: chloramphenicol toxicity revisited

We report here two cases of dyserythropoietic anaemia associated with long-term linezolid use that share striking similarities to chloramphenicol-associated myelotoxicity.

Glomerular abundance of nephrin and podocin in experimental nephrotic syndrome: different effects of antiproteinuric therapies

Nephrotic syndrome (NS) is a clinical state characterized by massive proteinuria, hypoalbuminemia, and eventual edema formation. Although the mechanisms underlying this phenomenon are not yet fully clarified, it is well accepted that nephrin and podocin are involved in the development of proteinuria. The effects of early treatment with various antiproteinuric therapies on proteinuria and glomerular staining of nephrin and podocin in rats with experimental NS have not been previously studied. Proteinuria and glomerular nephrin and podocin immunofluorescence were examined in rat kidneys with adriamycin-induced NS and the effects of antiproteinuric drug therapies during 5 wk with enalapril, losartan, alone or in combination, omapatrilat, and mycophenolate mofetil on these parameters were assessed. Injection of adriamycin caused a significant increase in daily (from 21.8 ± 1.4 to 983.1 ± 45.8 mg/day, P < 0.01) and cumulative protein excretion (from negligible values to 22,490 ± 931 mg, P < 0.001) during 5 wk. Early treatment with enalapril significantly decreased the daily (641.7 ± 82.4 mg/day, P < 0.0023) and cumulative proteinuria (15,727 ± 2,204 mg, P < 0.001). A similar effect, although to a lesser extent, was obtained after omapatrilat treatment: cumulative proteinuria was reduced to 18,706 ± 1,042 mg, P < 0.001. In contrast, losartan treatment did not significantly influence the cumulative proteinuria that remained comparable (20,351 ± 1,360 mg, P > 0.05) to that observed in untreated NS rats. Unexpectedly, when losartan was given in combination with enalapril, it abolished the beneficial effects of the latter. Pretreatment with mycophenolate mofetil exerted a moderate antiproteinuric effect, which appeared only during the last week of the experimental treatment. Nephrotic rats exhibited severe disruption of slit diaphragm structure as seen by rapid and profound loss of nephrin and podocin. Beneficial effects of enalapril, omapatrilat, and mycophenolate mofetil paralleled the preservation of nephrin, as determined immunohistochemically, and enabled prediction of significant antiproteinuric responses. Enalapril alone or in combination with losartan resulted in significant preservation of podocin. Pretreatment with enalapril, and to a lesser extent omapatrilat, is superior to losartan in reducing proteinuria in NS rats. A combination of ACE inhibitors with ANG II receptor blockers does not provide any advantageous antiproteinuric therapy in these animals. Nephrin loss is an indication of proteinuria in NS and the antiproteinuric effects of ACE inhibitors, vasopeptidase inhibitors, and mycophenolate mofetil attenuate this reduction. Not all the drugs which restore podocin reduce urinary protein in NS.

Transcriptional therapy with the histone deacetylase inhibitor trichostatin A ameliorates experimental autoimmune encephalomyelitis

We demonstrate that the histone deacetylase (HDAC) inhibitor drug trichostatin A (TSA) reduces spinal cord inflammation, demyelination, neuronal and axonal loss and ameliorates disability in the relapsing phase of experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). TSA up-regulates antioxidant, anti-excitotoxicity and pro-neuronal growth and differentiation mRNAs. TSA also inhibits caspase activation and down-regulates gene targets of the pro-apoptotic E2F transcription factor pathway. In splenocytes, TSA reduces chemotactic, pro-Th1 and pro-proliferative mRNAs. A transcriptional imbalance in MS may contribute to immune dysregulation and neurodegeneration, and we identify HDAC inhibition as a transcriptional intervention to ameliorate this imbalance.

CNS activity of Pokeweed anti-viral protein (PAP) in mice infected with lymphocytic choriomeningitis virus (LCMV)

Background

Others and we have previously described the potent in vivo and in vitro activity of the broad-spectrum antiviral agent PAP (Pokeweed antiviral protein) against a wide range of viruses. The purpose of the present study was to further elucidate the anti-viral spectrum of PAP by examining its effects on the survival of mice challenged with lymphocytic choriomeningitis virus (LCMV).

Methods

We examined the therapeutic effect of PAP in CBA mice inoculated with intracerebral injections of the WE54 strain of LCMV at a 1000 PFU dose level that is lethal to 100% of mice within 7–9 days. Mice were treated either with vehicle or PAP administered intraperitoneally 24 hours prior to, 1 hour prior to and 24 hours, 48 hours 72 hours and 96 hours after virus inoculation.

Results

PAP exhibits significant in vivo anti- LCMV activity in mice challenged intracerebrally with an otherwise invariably fatal dose of LCMV. At non-toxic dose levels, PAP significantly prolonged survival in the absence of the majority of disease-associated symptoms. The median survival time of PAP-treated mice was >21 days as opposed to 7 days median survival for the control (p = 0.0069).

Conclusion

Our results presented herein provide unprecedented experimental evidence that PAP exhibits antiviral activity in the CNS of LCMV-infected mice.

Pharmacodynamic profile of telithromycin against macrolide- and fluoroquinolone-resistant Streptococcus pneumoniae in a neutropenic mouse thigh model

The new ketolide telithromycin has potent in vitro activity against Streptococcus pneumoniae, including strains resistant to penicillin, macrolides, and fluoroquinolones. The aim of the present study was to define the pharmacodynamic profile of telithromycin against S. pneumoniae strains with various resistance profiles in an in vivo system. Ten S. pneumoniae strains were studied; seven exhibited penicillin resistance, six demonstrated macrolide resistance, and two exhibited gatifloxacin resistance. The telithromycin MICs for all isolates were < or =0.5 microg/ml. Using the murine thigh infection model, CD-1/ICR mice were rendered neutropenic and were then inoculated with 10(5) to 10(6) CFU of S. pneumoniae per thigh. Telithromycin was administered orally at doses ranging from 25 to 800 mg/kg of body weight/day, with the doses administered one, two, three, or four times a day. The activity of telithromycin was assessed by determination of the change in the bacterial density in thigh tissue after 24 h of treatment for each treatment group and the untreated controls. Pharmacokinetic studies of telithromycin were conducted in infected, neutropenic animals. The levels of protein binding by telithromycin in mice ranged from 70 to 95% over the observed range of pharmacokinetic concentrations. By using either the total or the free concentrations of telithromycin, the area under the concentration-time curve (AUC)/MIC ratio was a strong determinant of the response against S. pneumoniae, regardless of the phenotypic resistance profile. The maximal efficacy (the 95% effective dose) against this cohort of S. pneumoniae strains and bacterial inhibition (stasis) of telithromycin were predicted by ratios of the AUC for the free drug concentration/MIC of approximately 1,000 and 200, respectively.

Brain ischemic preconditioning is abolished by antioxidant drugs but does not up-regulate superoxide dismutase and glutathion peroxidase

The present work examined the hypothesis that brain ischemic tolerance induced by ischemic preconditioning (IPC) is triggered by an initial oxidative stress and is associated with an increase in antioxidant enzyme activities as one end-effector of the neuroprotection. Wistar rats were preconditioned by a single 3-min occlusion of the middle cerebral artery. After a various duration of reperfusion (30 min, 24, 72 or 168 h), rats were subjected to a 60-min focal ischemia and sacrificed 24 h later. Cerebral infarcts were significantly reduced when performed during the 24- to 72-h time window after IPC. The pretreatment with the protein synthesis inhibitor, cycloheximide (1 mg/kg, i.p., 30 min prior to IPC), completely suppressed the neuroprotection. The free radical scavenger, dimethylthiourea (DMTU; 300 mg/kg, i.p., 30 min prior to IPC) and the antioxidant ebselen (10 mg/kg, oral cramming, 2 h before and 12 h after IPC) also abolished the IPC-induced protection of the brain. Nevertheless, IPC did not induce any delayed changes in antioxidant enzyme (superoxide dismutase, glutathion peroxidase) activities nor in the neuronal expression of Mn and Cu/Zn superoxide dismutase. These results indicate that an initial oxidative stress could be involved as a trigger of IPC, while antioxidant enzymes do not play a key role as end-effectors in such a neuroprotection.

Newer antistaphylococcal agents

PURPOSE OF REVIEW

As antibiotic resistance in staphylococci continues to evolve, the ability to treat infections in children with confidence using first-generation cephalosporins, penicillins, and macrolides is decreasing. Knowledge of the local trends in resistance is important in making decisions of empiric antibiotic therapy. The antibiotic resistance pattern for the child's pathogen should be assessed whenever possible, to allow the practitioner to properly judge the risks and benefits of alternative antibiotic agents, should they be required for definitive therapy.

RECENT FINDINGS

Options for therapy of most methicillin-resistant and macrolide-resistant community-acquired strains of Staphylococcus aureus include vancomycin, linezolid, and, in communities with a high proportion of susceptible strains, clindamycin. Daptomycin, a lipopeptide antibiotic with activity against virtually all strains of S. aureus, was recently approved by the United States Food and Drug Administration for adults. Second-generation glycopeptide antibiotics similar to vancomycin are in clinical trials in adults, including dalbavancin and oritavancin. Several new compounds, including cephalosporins active against methicillin-resistant S. aureus, are in preclinical development as well.

SUMMARY

The recent worldwide emergence and rapid spread of community-acquired methicillin-resistant S. aureus has prompted a change in the approach to therapy of staphylococcal infections in both the outpatient clinic and the hospital. Newer agents active against methicillin-resistant S. aureus such as linezolid have been recently approved for children and other agents recently approved for adults are under investigation in children. Older agents for which relatively few data from prospective, controlled, comparative studies exist in the treatment of staphylococcal infections may also offer effective and less costly options for therapy.

Streptomycin and EDTA decrease the number of desmin-negative fibers following stretch injury

Streptomycin and ethylene diamine tetraacetic acid (EDTA) were used to examine the role of extracellular calcium in stretch-induced muscle injury. Streptomycin was injected in one group of rats, three times daily for 8 days (S, 300 mg.kg(-1).day(-1) intraperitoneally). In another group, EDTA was administered (150 mg.kg(-1) IP) 20 min before and 24 h after the injury protocol. Untreated rats (C) served as controls. Muscle injury was produced by 40 stretches of active dorsiflexor muscles by ankle rotation from 80 degrees to 130 degrees (velocity 1.75 rad.s(-1)). Ten minutes after the injury protocols, all animals lost the same amount of isometric force at both low and high stimulation frequencies (20 HZ; S, 56 +/- 6%; EDTA, 47 +/- 7%; C, 55 +/- 4%) and 120 HZ; S, 11 +/- 3%, EDTA, 13 +/- 3%; C, 11 +/- 3%). Tibialis anterior (TA) muscles were removed after 48 h for morphometric analysis. In both streptomycin-and EDTA-treated rats, the percent of injured (i.e., desmin-negative) myofibers in TA was reduced compared to untreated, injured muscles (S, 0.35 +/- 0.08%; EDTA, 0.64 +/- 0.19%; C, 1.81 +/- 0.43%). Thus, streptomycin and EDTA treatment did not alter the development of muscle weakness (i.e., isometric force deficit), but almost abolished the histopathologic changes. This study shows that the mechanisms for muscle weakness and histopathologic changes (inflammation) following repeated muscle strains can largely be dissociated from each other and helps explain why there is no correlation between isometric force deficits and the number of pathologic cells.

Down-regulation of amyloid precursor protein by peptide nucleic acid in vivo

Alzheimer's disease (AD) is a neurodegenerative disease associated with increased expression of amyloid precursor protein (APP) and the deposition of its proteolytic cleavage products, the amyloid-beta peptides, Abeta(1-40) and Abeta(1-42). Peptide nucleic acids (PNAs) have been shown to block the expression of proteins at transcriptional and translational levels. In this study we used a sense and an antisense PNA specifically targeted to APP to inhibit the transcription and translation of APP by complementary binding to DNA or mRNA, respectively. Using Western blotting, APP showed a drastic decrease (50% and 90% reduction, in two separate experiments, as compared with saline control) with the injection of sense APP. mRNA levels were higher at the same time point after injection of APP sense PNA, most probably because of a compensatory mechanism in response to the drop of APP that might have occurred at an earlier time point (0-1 h) and was reflected in a drop at the protein level at 1 h. The injection of antisense PNA showed about 70% decrease in APP as measured by Western blotting. Unmodified PNA can be used in vivo to reduce the levels of APP, which plays a critical role in the development of AD.

FDA-preapproved drugs targeted to the translational regulation and processing of the amyloid precursor protein

The 5' untranslated region (5'UTR) of the transcript encoding the Alzheimer's amyloid precursor protein (APP) is a key regulatory sequence that determines the amount of intracellular APP holoprotein present in brain derived cells. Using neuroblastoma cells (SY5Y) we developed a transfection based screen of a library of FDA drugs to identify compounds that limited APP luciferase reporter expression translated from the APP 5'UTR. Paroxetine (Paxil trade mark ), dimercaptopropanol, phenserine, desferrioxamine, tetrathiolmobdylate, and azithromycin were six leads that were subsequently found to also suppress APP holoprotein levels or to alter APP cleavage (azithromycin). Since APP holoprotein levels are proportionate to Abeta peptide output in many systems we tested the efficacy of paroxetine and dimercaptopropanol to limit Abeta secretion as measured by ELISA assays. Paroxetine and dimercaptopropanol limited Abeta peptide secretion from lens epithelial cells (B3 cells). Interestingly, paroxetine changed the steady-state levels of transferrin receptor mRNAs. These data suggested that this serotonin reuptake inhibitor (SSRI) provided extra pharmacological action to chelate interacellular iron or change the intracellular iron distribution. An altered iron distribution would be predicted to indirectly limit APP holoprotein expression and Abeta peptide secretion.

[Evaluation of Helicobacter pylori susceptibility to rifaximin]

INTRODUCTION

Helicobacter pylori infection affects more than half the world's population. It is a major cause of chronic gastritis and there is a strong association with peptic ulceration and gastric adenocarcinoma. Rifaximin is a new nonabsorbable broad-spectrum antimicrobial agent that reaches high concentrations in the gastrointestinal tract.

AIM

To evaluate the in vitro activity of rifaximin against H. pylori isolates.

METHODS

Thirty-one H. pylori strains were analyzed by the agar dilution method. Clarithromycin was used as the control antibiotic. Staphylococcus aureus and Streptococcus pneumoniae were used as quality control strains. Plates were read at days 4 and 7 of incubation. The MIC50 and MIC90 of each antibiotic were calculated. Strains with a clarithromycin MIC of > 1 microg/ml were considered resistant.

RESULTS

The MIC50 of clarithromycin at days 4 and 7 was 0.125 microg/ml and the MIC90 at days 4 and 7 ranged from 8 to 16 microg/ml, respectively. The MIC50 of rifaximin at days 4 and 7 ranged from 1 to 2 microg/ml, respectively, and the MIC90 was 4 microg/ml at both days 4 and 7. Twenty percent of H. pylori strains were resistant to clarithromycin. All clarithromycin-resistant strains were inhibited at a maximal rifaximin concentration of 4 microg/ml.

CONCLUSION

These results indicate that this new antibiotic may be useful for eradication of H. pylori infection. Because rifaximin is active against H. pylori strains resistant to clarithromycin, it could be useful in combination with this drug or in the treatment of therapeutic failure.

Linezolid

Linezolid is an oxazolidinone antibacterial agent that acts by inhibiting the initiation of bacterial protein synthesis. Linezolid has a wide spectrum of activity against gram-positive organisms including methicillin resistant staphylococci, penicillin resistant pneumococci and vancomycin resistant enterococcus faecalis and E. faecium. Linezolid has a good bio-availability orally and could be switched from parenteral to oral therapy while treating serious infections. Linezolid is well tolerated in children.

Ureteral replacement using small-intestinal submucosa and a collagen inhibitor in a porcine model

PURPOSE

Small-intestinal submucosa (SIS) has been successful as an onlay graft in ureteral repair, but tubularized segment interposition of SIS has been unsuccessful. Our objective was to evaluate whether a type I collagen inhibitor, halofuginone, would prevent stricture formation in tubularized SIS interposition.

MATERIALS AND METHODS

We performed either laparoscopic partial ureteral excision followed by an SIS onlay graft (N = 5) or complete laparoscopic ureteral excision followed by an SIS interposition graft (N = 7) in domestic pigs. Animals received either no (N = 3), low-dose (N = 5), or high-dose (N = 4) halofuginone. Animals had ureteral stenting for 2 weeks after surgery and were permitted to survive for 6 or 9 weeks. An intravenous urogram (IVU) was performed prior to sacrifice. Kidneys were examined grossly and histologically.

RESULTS

One animal that received an onlay graft died of an unrelated illness. The remaining four ureteral onlay animals, including one control and two low-dose and one high-dose pig, had grossly normal kidneys at harvest. The IVU was normal in the control and high-dose animal but showed delayed excretion with mild hydroureteronephrosis in the low-dose animals. Pathologic examination of the SIS site revealed circumferential reepithelialization with inflammation and mild fibrosis. All seven tubularized interposition graft kidneys demonstrated either severe hydroureteronephrosis (N = 5) or renal atrophy (N = 2), and all had complete obstruction on IVU. Pathologic examination revealed a stenotic ureteral lumen with extensive surrounding inflammation and fibrosis.

CONCLUSIONS

An SIS onlay graft was successful in the porcine model of ureteral injury. Halofuginone, a type I collagen inhibitor, did not demonstrate a significant beneficial effect in this technique. Ureteral tubularized interpositions with SIS are unsuccessful and not improved by halofuginone.

Aneurysmal subarachnoid hemorrhage in a patient with Wegener?s granulomatosis

A 34-year-old Japanese man admitted to hospital with pneumonia had previously undergone surgery for paranasal sinusitis and also for the clipping of an aneurysm at the origin of the anterior choroidal artery after subarachnoid hemorrhage. Laboratory tests performed at the present admission showed renal insufficiency and serological findings of raised proteinase 3 antineutrophil cytoplasmic antibody level. A renal biopsy was performed that showed diffuse necrotizing glomerulonephritis with fibrocellular crescents. The diagnosis of Wegener's granulomatosis(WG) was confirmed on the basis of the clinical picture, laboratory findings, and biopsies of renal tissues. The disease responded to prednisolone and cyclophosphamide. The association of WG with a ruptured intracranial aneurysm is rare and has not previously been confirmed.

The behavioral deficit observed following noncontingent shock in spinalized rats is prevented by the protein synthesis inhibitor cycloheximide

Spinalized rats that receive shock when 1 hind limb is extended (contingent shock) exhibit an increase in flexion duration, a simple form of instrumental learning. Rats that receive shock independent of leg position (noncontingent shock) do not exhibit an increase in flexion duration and fail to learn when tested with contingent shock 24 hr later. It appears that noncontingent shock induces an intraspinal modification that inhibits the capacity to learn. The authors propose that the mechanisms that underlie this effect depend on de novo protein synthesis. To evaluate this hypothesis, the authors gave spinalized rats the protein synthesis inhibitor Cycloheximide (CXM) or saline intrathecally prior to, or immediately after, noncontingent shock exposure. Twenty-four hours later, rats were tested with contingent shock. Rats that received the vehicle and noncontingent shock failed to learn. CXM-treated shocked rats learned normally, suggesting that the learning deficit depends on protein synthesis within the spinal cord.

Efficacy and tolerability of linezolid in treating severe skin and soft tissue infections caused by Gram-positive pathogens

BACKGROUND AND PURPOSE

Linezolid, an oxazolidinone, has shown efficacy in the treatment of adults with nosocomial or community-acquired pneumonia; skin and soft tissue infections; and infections due to methicillin-resistant Staphylococcus aureus. The purpose of this open-label, single-arm, multicenter study was to evaluate the efficacy and tolerability of linezolid in patients from the Asia-Pacific Region with severe Gram-positive skin and soft tissue infections.

METHODS

166 patients at 27 sites in 7 countries from the Asia-Pacific region were enrolled. The patients had severe skin infection involving the deeper layers or extensive surface area. Patients received 7 to 28 days of treatment with linezolid by clinical judgment. All patients received intravenous linezolid 600 mg twice a day initially and were switched over to an equivalent oral dose (600 mg twice a day) when the investigator discerned clinical improvement. The primary efficacy endpoint in this study was clinical outcome at the follow-up visit, 14 to 21 days after completion of treatment (test of cure), and the secondary efficacy variable was microbiologic response at test-of-cure.

RESULTS

166 patients received the study medication and were included in the intent-to-treat analysis. The clinical success rate was approximately 93% in both the intent-to-treat and clinically evaluable populations at the end of treatment and test-of-cure visits. In the modified intent-to-treat and microbiologically evaluable populations, the microbiologic success rates at the test-of-cure visit were 88.9% and 93.8%, respectively. The most frequent treatment-emergent adverse events were nausea (13%), dizziness (8%), anemia (7%), and vomiting (5%).

CONCLUSIONS

Linezolid was effective and well tolerated in patients with severe skin and soft tissue infections caused by Gram-positive pathogens.

Lincomycin, clindamycin and their applications

Lincomycin and clindamycin are lincosamide antibiotics used in clinical practice. Both antibiotics are bacteriostatic and inhibit protein synthesis in sensitive bacteria. They may even be bactericidal at the higher concentrations that can be reached in vivo. Clindamycin is usually more active than lincomycin in the treatment of bacterial infections, in particular those caused by anaerobic species; and it can also be used for the treatment of important protozoal diseases, e.g. malaria, most effectively in combination with primaquine. Resistance to lincomycin and clindamycin may be caused by methylation of 23S ribosomal RNA, modification of the antibiotics by specific enzymes or active efflux from the periplasmic space.

Amelioration of radiation-induced fibrosis: inhibition of transforming growth factor-beta signaling by halofuginone

Radiation-induced fibrosis is an untoward effect of high dose therapeutic and inadvertent exposure to ionizing radiation. Transforming growth factor-beta (TGF-beta) has been proposed to be critical in tissue repair mechanisms resulting from radiation injury. Previously, we showed that interruption of TGF-beta signaling by deletion of Smad3 results in resistance to radiation-induced injury. In the current study, a small molecular weight molecule, halofuginone (100 nm), is demonstrated by reporter assays to inhibit the TGF-beta signaling pathway, by Northern blotting to elevate inhibitory Smad7 expression within 15 min, and by Western blotting to inhibit formation of phospho-Smad2 and phospho-Smad3 and to decrease cytosolic and membrane TGF-beta type II receptor (TbetaRII). Attenuation of TbetaRII levels was noted as early as 1 h and down-regulation persisted for 24 h. Halofuginone blocked TGF-beta-induced delocalization of tight junction ZO-1, a marker of epidermal mesenchymal transition, in NMuMg mammary epithelial cells and suggest halofuginone may have in vivo anti-fibrogenesis characteristics. After documenting the in vitro cellular effects, halofuginone (intraperitoneum injection of 1, 2.5, or 5 microg/mouse/day) efficacy was assessed using ionizing radiation-induced (single dose, 35 or 45 Gy) hind leg contraction in C3H/Hen mice. Halofuginone treatment alone exerted no toxicity but significantly lessened radiation-induced fibrosis. The effectiveness of radiation treatment (2 gray/day for 5 days) of squamous cell carcinoma (SCC) tumors grown in C3H/Hen was not affected by halofuginone. The results detail the molecular effects of halofuginone on the TGF-beta signal pathway and show that halofuginone may lessen radiation-induced fibrosis in humans.

Combination therapy of tetracycline and tacrolimus resulting in rapid resolution of steroid-induced periocular rosacea

Standard treatment of steroid-induced rosacea includes discontinuation of steroids and use of an oral tetracycline. A temporary decrease to a lower-potency steroid prior to discontinuation remains optional. The limitations of standard therapy include a prolonged course of treatment with exacerbations prior to permanent improvement. Our challenge was to identify a treatment regimen to resolve steroid-induced periocular rosacea quickly and with minimal rebound effect.

Inhibitory actions of genistein in human breast cancer (MCF-7) cells

Genistein, a natural isoflavanoid phytoestrogen, is thought to be the active ingredient in soy that possesses breast cancer preventive properties. The molecular mechanisms that are involved in its cancer preventive properties have not been completely understood. The present study is designed to investigate the mechanism involved in the inhibitory action of genistein in MCF-7 cells. Genistein at 50 and 100 microM significantly arrested the growth of MCF-7 cells at G2/M phase (P<0.05) and decreased at the proliferative S phase (P<0.05). Using cDNA microarray technology, genes differentially regulated by genistein were identified. In particular, as confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR), genistein up-regulated heat shock protein 105 (HSP) mRNA and down-regulated mRNA expression of serum response factor (SRF), estrogen receptor (ER) alpha, disabled homolog 2 (DOC 2) and recombination activation gene 1 (RAG-1). Using real time RT-PCR, we have shown that HSP and SRF mRNA were both regulated by genistein in a time- and dose-dependent manner; however, it appears that only the effect of genistein on SRF mRNA, but not HSP mRNA expression, can be partially abolished by cotreatment with estrogen antagonist ICI 182,780. Western blotting analysis showed that the expressions of the ERalpha and SRF protein decreased significantly with genistein treatment (P<0.05). These results suggest that the inhibitory action of genistein on human breast cancer cells appears to be complex and is only partially mediated by the alteration of estrogen receptor-dependent pathways.

Halofuginone to treat fibrosis in chronic graft-versus-host disease and scleroderma

Chronic graft-versus-host disease (cGvHD) and systemic sclerosis (scleroderma [SSc]) share clinical characteristics, including skin and internal organ fibrosis. Fibrosis, regardless of the cause, is characterized by extracellular matrix deposition, of which collagen type I is the major constituent. The progressive accumulation of connective tissue results in destruction of normal tissue architecture and internal organ failure. In both SSc and cGvHD, the severity of skin and internal organ fibrosis correlates with the clinical course of the disease. Thus, there is an unmet need for well-tolerated antifibrotic therapy. Halofuginone is an inhibitor of collagen type I synthesis in cells derived from various tissues and species and in animal models of fibrosis in which excess collagen is the hallmark of the disease. Halofuginone decreased collagen synthesis in the tight skin mouse (Tsk) and murine cGvHD, the 2 experimental systems that show many features resembling those of human GvHD. Inhibition of collagen synthesis by halofuginone is achieved by inhibiting transforming growth factor beta-dependent Smad3 phosphorylation. Dermal application of halofuginone caused a decrease in collagen content at the treated site of a cGvHD patient, and reduction in skin scores was observed in a pilot study with SSc patients. The results of the human studies provide basis for using halofuginone treatment for dermal fibrosis. As a first step toward future treatment of internal organ involvement, an oral administration study was performed in which halofuginone was well tolerated and plasma levels surpassed the predicted therapeutic exposure.

Worldwide assessment of linezolid's clinical safety and tolerability: comparator-controlled phase III studies

Linezolid, an oxazolidinone antibiotic, has 100% oral bioavailability and favorable activities against gram-positive pathogens including multidrug-resistant staphylococci, enterococci, and pneumococci. Safety assessments were conducted for 2,046 linezolid-treated patients and 2,001 comparator drug-treated patients from seven controlled clinical trials comparing the activities of linezolid and comparator drugs against nosocomial and community-acquired pneumonia, skin and skin structure infections, and methicillin-resistant staphylococcal infections. Drug-related adverse events were primarily transient. The most frequent (> or = 2%) adverse events caused by linezolid and the comparator drugs were diarrhea (4.3 and 3.2%, respectively; P = 0.074), nausea (3.4 and 2.3%, respectively; P = 0.036), and headache (2.2 and 1.3%, respectively; P = 0.047). Treatment discontinuations due to drug-related events (2.4 and 1.9%, respectively), serious adverse events (11.4 and 10.6%, respectively), and deaths (4.8 and 4.9%, respectively) were similar. No clinically significant drug-related hematologic events were reported, and laboratory safety data were comparable. In the first 6 months of postmarketing surveillance, hematologic abnormalities were reported in 0.1% of linezolid-treated patients, but no irreversible blood dyscrasias were documented. The risk for transient, reversible hematologic effects from treatment with linezolid should be considered together with the clinical benefits associated with its use.

Targeting bacterial virulence: the role of protein synthesis inhibitors in severe infections. Insights from the Society of Infectious Diseases Pharmacists

Morbidity and mortality due to certain bacterial pathogens have not declined despite the availability of effective antimicrobial treatments. Staphylococcus aureus and Streptococcus pyogenes cause a number of serious infections, such as necrotizing fasciitis and toxic shock syndrome, which are associated with the release of bacterial toxins. Animal studies have demonstrated clindamycin, a protein synthesis inhibitor, to be more effective in treating these severe infections than other more susceptible antimicrobial treatments. Linezolid, another protein synthesis inhibitor, also has shown efficacy in in vitro studies. Human trials to validate the effects of antibiotic therapies on bacterial virulence have not been performed. Future animal and human studies are needed to help elucidate the immunomodulatory mechanisms of protein synthesis inhibitors in order to optimize antimicrobial treatment and decrease the morbidity and mortality associated with severe bacterial infections.

[Macrolides, ketolides and streptogramins]

Macrolides, ketolides and streptogramins are three families of antibiotics with different chemical structures, sharing the same mechanism of action. All three bind to distinct bases of the peptidyl transferase center of ARNr 23S. Their antibacterial spectrum practically overlaps, but dissimilarities in affinity and/or number of binding sites determine differences in the intensity of their antibacterial effects (bacteriostatic or bactericidae) and in their activity against strains with acquired resistance mechanisms. These agents are active against the majority of gram-positive microorganisms and many intracellular microorganisms for growth. Over the last five years in our country, the percentage of macrolide-resistant pneumococci and S. pyogenes strains has increased substantially. Telithromycin (ketolide) and Synercid (streptogramin) have shown maintained activity against these strains. Macrolides, ketolides and streptogramins are metabolized in the liver through CYP 3A4 and they can partially block the activity of the enzyme, interfering with the metabolism of other drugs that use the same metabolic pathway. There is little elimination through the urine, with the exception of clarithromycin. High concentrations are reached in the cellular cytoplasm, but they do not diffuse to the CSF. These agents are included among class B drugs for use during pregnancy. Tolerance to macrolides and telithromycin is good and they have few associated adverse effects. The main clinical indication for these drugs is in empirical treatment of mild to moderate, community-acquired, upper and lower respiratory tract infections. Synercid is indicated in the treatment of infections due to methicillin-resistant staphylococci and glycopeptide-resistant enterococci.

Novel antibacterial agents for the treatment of serious Gram-positive infections

With the continuing development of clinical drug resistance among bacteria and the advent of resistance to the recently released agents quinupristin-dalfopristin and linezolid, the need for new, effective agents to treat multi-drug-resistant Gram-positive infections remains important. This review focuses on agents presently in clinical development for the treatment of serious multidrug-resistant staphylococcal, enterococcal and pneumococcal infections, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae. Agents to be discussed that affect the prokaryotic cell wall include the antimethicillin-resistant S. aureus cephalosporins BAL9141 and RWJ-54428, the glycopeptides oritavancin and dalbavancin and the lipopeptide daptomycin. Topoisomerase inhibitors include the fluoroquinolones gemifloxacin, sitafloxacin and garenoxacin. Protein synthesis inhibitors are represented by the ketolides telithromycin and cethromycin, the oxazolidinones and the glycylcycline tigecycline. Although each of these compounds has demonstrated antibacterial activity against antibiotic-resistant pathogens, their final regulatory approval will depend on an acceptable clinical safety profile.

[Oxazolidinones and glycopeptides]

We review the chemical structure, pharmacokinetics, antimicrobial spectrum, mechanisms of action and resistance, clinical use and adverse effects of oxazolidinones (linezolid) and glycopeptides. Oxazolidinones inhibit protein synthesis and glycopeptides cell wall synthesis. Antibacterial spectra cover grampositive pathogens, including multiresistant organisms. Linezolid has a 100% absorption and can be administered orally or intravenously; it is cleared by renal and hepatic routes, thus dose adjustments are not needed in moderate renal or hepatic failure. Oral absorption of glycopeptides is minimal. They are excreted by the kidneys (dose adjustments are needed in renal failure). The main clinical indications are the treatment of infections caused by grampositive pathogens; linezolid is also useful for infections caused by glycopeptide-resistant enterococcal infections. Linezolid can cause trombocytopenia when treatment lasted longer than two weeks. The main side effect of vancomycin is its nefrotoxicity and teicoplanin can cause fever.

Neuroprotective synergy of N-methyl-D-aspartate receptor antagonist (MK801) and protein synthesis inhibitor (cycloheximide) on spinal cord ischemia-reperfusion injury in rats

Thoraco-abdominal aortic surgery requiring temporal cross clamping of the aorta results in a high incidence of paraplegia due to temporary ischemia of the spinal cord. Both excitotoxicity and apoptosis are implicated in the pathogenesis of spinal cord ischemia-reperfusion injury. We propose that the N-methyl-D-aspartate receptor antagonist dizocilpine maleate (MK801) and the protein synthesis inhibitor cycloheximide produce a synergic effect in a rodent model of spinal cord ischemia-reperfusion injury. Injury was induced by 20 min of temporal thoracic aorta occlusion and distal blood volume reduction. After injury, the animals were treated with vehicle, MK801, cycloheximide or MK801 and cycloheximide. Hind limb motor function recovery was better in the MK801 and combined therapy groups than in the control and cycloheximide groups. The mean neuronal survival rate of the control group was 45.3 +/- 3.2% on the 7(th) day after injury. In the MK801 and cycloheximide treatment groups, neuronal survival increased to 62.4 +/- 3.6% and 54.1 +/- 2.4%, respectively. For the combined therapy group, neuronal survival increased to 75.6 +/- 2.5%. The number of apoptotic cells in the control group was 211.4 +/- 8.8 per section on the 7th day after ischemic insult, while apoptosis was significantly reduced in the cycloheximide (96.8 +/- 6.7 cells) and combined (84.8 +/- 8.5 cells) groups. It was unchanged in the MK801 group (209.8 +/- 5.4 cells). These results suggest that combined treatments directed at blocking both N-methyl-D-aspartate receptor-mediated excitotoxic necrosis and caspase-mediated apoptosis might have synergic therapeutic potential in reducing spinal cord ischemia-reperfusion injury.

Autologous blood cell transplantation in multiple myeloma: impact of CD34+ cell selection with long follow-up

Positive CD34(+) selection to purge blood cell harvests is one way to attempt to reduce the high relapse risk after high-dose chemotherapy (HDT) supported by autologous blood cell transplantation (ABCT) in patients with multiple myeloma (MM). Until recently, however, the impact of CD34(+) selection, if any, on long-term clinical outcome in MM has remained obscure. We have analyzed engraftment kinetics, response to HDT, progression-free survival (PFS), and overall survival (OS) for 64 consecutive MM patients who have been treated with up-front HDT plus ABCT at our institution between 1993 and 1998. Nonrandomized comparisons were made between transplants with unselected (39 patients) and CD34(+)-selected (25 patients) grafts. The engraftment kinetics, need of blood product support, discharge time from hospital, and response to HDT were similar for both unselected and selected transplants. The median PFS was also similar (26 and 30 months, respectively) for the both groups. With a median follow-up time for the survivors of 67.5 months, the median OS (78 and 75 months, respectively) did not differ between transplants with unselected and selected grafts. In conclusion, this nonrandomized study suggests that positive CD34(+) selection has no beneficial impact on long-term outcome of patients with MM.

Small-molecule inhibitors of the cell cycle: an overview

Potent and selective small-molecule mediated inhibition of the cell's replication machinery remains a principal aim in the development of novel therapeutics and biological probes. Recent efforts have identified small molecules capable of arresting the cell cycle via specific interaction with a variety of intracellular protein targets. Advances in combinatorial and diversity oriented synthetic methods, coupled with a continued effort to identify sources of bioactive natural products, promise to contribute to the growing library of small-molecule inhibitors of the cell cycle.

Changes in immune parameters and their correction in human cases of tick-borne encephalitis

Tick-Borne Encephalitis virus (TBEV) causes dangerous central nervous system diseases in humans. General infection leads to the development of meningitis or encephalitis, which is characterized by swelling of the brain due to inflammation. Tetracyclines may act locally to moderate inflammation in the CNS. In this study, we investigated the potential clinical benefits of administering tetracycline hydrochloride to patients hospitalized due to suspected TBEV infection presenting with fever and evidence of a recent tick bite. We also characterized an acute immune response to TBEV by profiling certain cytokines and soluble receptors in Tetracycline-treated and untreated patients. Increased serum levels of TNF-alpha, IL-1 alpha and IL-6 were found in all patients at admission. Soluble receptors presented in the serum of patients in a magnitude higher levels than the corresponding cytokines and were increasing during first weak of hospitalization. Levels of IL-10 were also rising during that period. In our study tetracycline hydrochloride acted as an immunomodulator, which was able to reduce manifestations of inflammation response during TBE course; this action led to quicker improvement of symptoms and, consequently, to a faster clinical recovery. The positive result of tetracycline hydrochloride treatment was accompanied by certain particularities in the dynamics of studied cytokines and receptors: the concentrations of IL-6, IL-1 beta, TNF-alpha dropped quicker and reached lower levels, and the concentrations of sIL-6R, IL-1RA, sTNFR1 increased faster and reached higher maximum levels in the tetracycline-treated groups. Children had the highest levels of IL-6, which were not neurotoxic.