Hippo/YAP signaling pathway protects against neomycin-induced hair cell damage in the mouse cochlea

The Hippo/Yes-associated protein (YAP) signaling pathway has been shown to be able to maintain organ size and homeostasis by regulating cell proliferation, differentiation, and apoptosis. The abuse of aminoglycosides is one of the main causes of sensorineural hearing loss (SSNHL). However, the role of the Hippo/YAP signaling pathway in cochlear hair cell (HC) damage protection in the auditory field is still unclear. In this study, we used the YAP agonist XMU-MP-1 (XMU) and the inhibitor Verteporfin (VP) to regulate the Hippo/YAP signaling pathway in vitro. We showed that YAP overexpression reduced neomycin-induced HC loss, while downregulated YAP expression increased HC vulnerability after neomycin exposure in vitro. We next found that activation of YAP expression inhibited C-Abl-mediated cell apoptosis, which led to reduced HC loss. Many previous studies have reported that the level of reactive oxygen species (ROS) is significantly increased in cochlear HCs after neomycin exposure. In our study, we also found that YAP overexpression significantly decreased ROS accumulation, while downregulation of YAP expression increased ROS accumulation. In summary, our results demonstrate that the Hippo/YAP signaling pathway plays an important role in reducing HC injury and maintaining auditory function after aminoglycoside exposure. YAP overexpression could protect against neomycin-induced HC loss by inhibiting C-Abl-mediated cell apoptosis and decreasing ROS accumulation, suggesting that YAP could be a novel therapeutic target for aminoglycosides-induced sensorineural hearing loss in the clinic.

Linezolid-Associated Serotonin Syndrome After Concomitant Treatment With Citalopram and Mirtazepine in a Critically Ill Bone Marrow Transplant Recipient

Linezolid was initially discovered as an antidepressant because of its effect on blocking intracellular metabolism of serotonin, norepinephrine, and other biogenic amines. As time passed, it was realized that linezolid possessed antibacterial activity, and linezolid has been developed and marketed as such. In medicine we are quick to categorize drugs into specific classes as a mechanism to recall indication and use. By classifying linezolid as an antibacterial, it is common to forget about its antidepressant roots. A case report involving linezolid with citalopram and mirtazepine in the precipitation of serotonin syndrome in a critically ill bone marrow transplant patient is described in this article.

Does long-term chloramphenicol cause anaemia in Malawi?

Common clinical practice in many tropical paediatric departments is that chloramphenicol courses are limited to 2 weeks due to concerns about anaemia. However, this approach is not supported by current research and animal models. We used chloramphenicol for 6 weeks in 146 children with septic arthritis. All the children improved clinically. Most children were anaemic on presentation (mean haemoglobin [Hb] 8.43 SD 1.9), but the anaemia improved rapidly with clinical resolution of the infection and was maintained at 6 months after presentation (mean Hb 10.57 SD 1.86).

[Protective effect of selank on the model of mnestic function violation induced by pharmacological blockade of protein synthesis]

We have studied the ability of peptide anxiolytic selank (Thr-Lyz-Pro-Arg-Pro-Gly-Pro) to compensate for mnestic dysfunction caused by the administration of actinomycin D, which inhibits protein synthesis by blocking DNA-dependent RNA polymerase. The experiments were performed on white rats with acquired adaptive ability of spatial visual orientation in a 16-door labyrinth. The learning was based on the avoidance of electric skin irritation at alternating sites of escape reaction (site reflex). Selank (0.5 mg/kg, i.p.) prevented or compensated for actinomycin D (250 mg/kg, i.p.) induced violation of the process of acquisition, improvement, and consolidation of memory trace during the development of a complex site reflex. The drug administration also reduced the time required for acquisition of the adaptive ability of spatial visual orientation in the labyrinth and restored the actinomycin D violated process of re-learning upon a change in the alternation of escape sites under free-choice conditions.

Passive avoidance impairment in rats following cycloheximide injection into the amygdala

Cycloheximide (CHX:1, 10 or 20 microg) was injected via indwelling cannulas into various regions of the rat brain and its effects on passive avoidance training were studied. Rats with 10 or 20 microg of CHX injected into the amygdala immediately after the training footshock exhibited amnesia for the learning experience when tested after 24 h. In contrast, animals injected with 20 microg of CHX at a site either in the internal capsule only 2 mm above the amygdaloid injection site or in the frontal cortex showed no retention deficit when tested after 24 h. A quantitative examination of protein synthesis in brain halves 30 min after unilateral injection of 20 microg of CHX into the amygdala demonstrated that total protein synthesis was inhibited by less than 10%. Autoradiographic studies revealed that this inhibition resulted from a profound, highly localized inhibition of protein synthesis in areas immediately adjacent to the cannula. A comparison of the regional patterns of protein synthesis inhibition caused by injection of CHX into either the amygdala or internal capsule suggested that CHX might produce amnesia by virtue of its localized effect on the amygdala. Control experiments revealed that injection of 20 microg CHX into the amygdala had no effect on short-term retention, or short-term performance. Injection of 20 microg of CHX into the amygdala 12 h after the footshock had no effect on long-term retention. The observed impairment of retention was shown to be dose-dependent as injection of 1 microg of CHX into the amygdala was without effect. In addition, it was demonstrated that the CHX-induced amnesia did not result from induction of local seizure activity. These data show that localized injections of small amounts of CHX into the amygdala can produce deficient memory of a training experience even though total brain protein synthesis is only slightly inhibited.

High-dose intratympanic gentamicin instillations for treatment of Meniere's disease: long-term results

CONCLUSIONS

Administration of high-dose gentamicin for intractable Meniere's disease appears to be effective in achieving long-term control of vertigo. However, the safety of this route of administration with respect to the patient's hearing has not yet been sufficiently established.

OBJECTIVES

The study aimed to analyze the long-term results of patients receiving high-dose intratympanic gentamicin (ITG) instillation for refractory Meniere's disease.

PATIENTS AND METHODS

Fourteen patients with Meniere's disease according to 1995 American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines who had failed medical (12 subjects) or surgical (2 subjects) treatment were included. Intratympanic injections of 27 mg/ml gentamicin were performed three times daily for 4 days. Vertigo control, the patients' functional level, and their hearing threshold were all analyzed. Criteria described in 1995 by AAO-HNS were used.

RESULTS

The overall successful vertigo control rate was 92.9% over the 2-year follow-up and 85.7% at long-term follow-up (average 10 years). Hearing level as pure-tone average was worse in four patients (28.5%) after 2 years follow-up and in six patients (42.8%) after long-term follow-up, respectively. Profound sensorineural hearing loss occurred as a result of gentamicin injection in one patient (7%).

Post-learning infusion of anisomycin into the anterior cingulate cortex impairs instrumental acquisition through an effect on reinforcer valuation

The integrity of the rodent anterior cingulate cortex (ACC) is essential for various aspects of instrumental behavior, but it is not clear if the ACC is important for the acquisition of a simple instrumental response. Here, it was demonstrated that post-session infusions of anisomycin into the rat ACC completely prevented the acquisition of instrumental responding. The experimental use of post-session intracranial infusions of plasticity inhibitors is assumed to affect local consolidation of plasticity, but not behavioral task performance. However, in associative appetitive conditioning, post-session intracranial infusion of pharmaco-active compounds could actually interfere with subsequent task performance indirectly through retrospective effects on the valuation of ingested rewards. Thus, it was subsequently demonstrated that the intracranial infusion of anisomycin into the ACC after sucrose pellet consumption significantly reduced subsequent pellet consumption, suggesting that the infusion of anisomycin into the ACC produced conditioned taste avoidance. In the third experiment, an innovative procedure was introduced that dissociated the effects of intracranial infusions after conditioning sessions on task-learning and unconditioned stimulus valuation. With this procedure, the infusion of anisomycin into the ACC after instrumental sessions did not affect instrumental reinforcer valuation or the acquisition of instrumental responding, suggesting that plasticity in the ACC is not necessary for the acquisition of instrumental behavior.

Supporting cell characteristics in long-deafened aged mouse ears

Significant sensory hair cell loss leads to irreversible hearing and balance deficits in humans and other mammals. Future therapeutic strategies to repair damaged mammalian auditory epithelium may involve inserting stem cells into the damaged epithelium, inducing non-sensory cells remaining in the epithelium to transdifferentiate into replacement hair cells via gene therapy, or applying growth factors. Little is currently known regarding the status and characteristics of the non-sensory cells that remain in the deafened auditory epithelium, yet this information is integral to the development of therapeutic treatments. A single high-dose injection of the aminoglycoside kanamycin coupled with a single injection of the loop diuretic furosemide was used to kill hair cells in adult mice, and the mice were examined 1 year after the drug insult. Outer hair cells are lost throughout the entire length of the cochlea and less than a third of the inner hair cells remain in the apical turn. Over 20% and 55% of apical organ of Corti support cells and spiral ganglion cells are lost, respectively. We examined the expression of several known support cell markers to investigate for possible support cell dedifferentiation in the damaged ears. The support cell markers investigated included the microtubule protein acetylated tubulin, the transcription factor Sox2, and the Notch signaling ligand Jagged1. Non-sensory epithelial cells remaining in the organ of Corti retain acetylated tubulin, Sox2 and Jagged1 expression, even when the epithelium has a monolayer-like appearance. These results suggest a lack of marked SC dedifferentiation in these aged and badly damaged ears.

[Serotonin syndrome associated with linezolid use: a case report]

The serotonin syndrome is a toxic state largely attributable to changes in sensitivity of serotonin receptor system in the brainstem and spinal cord resulting from increased serotonergic activity in central neurologic system, due to use of serotonergic agents either in overdose or in combination. Serotonin syndrome may present with neuromuscular (clonus, myoclonus, tremor, hyperreflexia) and autonomic (fever, mydriasis, tachycardia, tachypnea) symptoms and mental status changes (confusion, agitation) and may result in death in severe cases. The risk for the development of serotonin syndrome is increased with the combined use of agents from different groups such as selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs). The growing use of SSRIs for depression and the introduction of pharmacological agents newly developed for the treatment of various medical disorders increases the risk of drug-drug interactions and toxic states like serotonin syndrome. In the presented case clinical presentation and outcome of the serotonin syndrome which has developed as a consequence of concomitant linezolid use in a young patient who was already on an SSRI antidepressant is discussed. Linezolid is an oxazolidinone antibiotic which has MAOI-like properties. This case is presented to inform psychiatrists especially working in consultation-liaison settings about the risk of drug-drug interactions and possible prevention of these.

Protein synthesis inhibitors, gene superinduction and memory: too little or too much protein?

To date, the effects of protein synthesis inhibitors (PSI) in learning and memory processes have been attributed to translational arrest and consequent inhibition of de novo protein synthesis. Here we argue that amnesia produced by PSI can be the direct result of their abnormal induction of mRNA-a process termed gene superinduction. This action exerted by PSI involves an abundant and prolonged accumulation of mRNA transcripts of genes that are normally transiently induced. We summarize experimental evidence for the multiple mechanisms and signaling pathways mediating gene superinduction and consider its relevance for PSI-induced amnesia. This mechanistic alternative to protein synthesis inhibition is compared to models of electroconvulsive seizures and fragilexsyndrome associated with enhanced mRNA/protein levels and cognitive deficits.

Reconsolidation of a long-term spatial memory is impaired by cycloheximide when reactivated with a contextual latent learning trial in male and female rats

Reconsolidation of long-term memory has become a topic of great interest in recent years, and has the potential to provide important information regarding memory processes and the treatment of memory-related disorders. The present study examined the role of systemic protein synthesis inhibition in reconsolidation of a long-term spatial memory reactivated by a contextual latent learning trial in male and female rats. Using the Morris water maze, we demonstrate that: 1) a contextual latent reactivation treatment enhances memory, 2) systemic protein synthesis inhibition selectively impairs test performance when administered in conjunction with a memory reactivation treatment, and 3) that these effects are more pronounced in female rats. These findings indicate a role for protein synthesis in the reconsolidation of a contextually reactivated long-term spatial memory using the water maze, and a potential differential effect of sex in this apparatus. The role of the strength of the memory trace is discussed and the relevance of these findings to theories of reconsolidation and therapeutic treatment of post-traumatic stress disorder is discussed.

Reversible inactivation of amygdala and cerebellum but not perirhinal cortex impairs reactivated fear memories

The cerebellum, amygdala and perirhinal cortex are involved in fear learning but the different roles that these three structures play in aversive learning are not well defined. Here we show that in adult rats amygdala or cerebellar vermis blockade causes amnesia when performed immediately, but not 1 h, after the recall of fear memories. Thus, the cerebellum, as well as the amygdala, influences long-term fear memories. These effects are long lasting, as they do not recover over time, even after a reminder shock administration. However, all of the subjects were able to form new fear memories in the absence of inactivation. By increasing the strength of conditioning, we observed that stronger fear memories are affected by the combined but not independent amygdala and cerebellar blockade. These results demonstrate that the cerebellum supports the memory processes even in the absence of a crucial site for emotions like the amygdala. Furthermore, they suggest that the amygdala is only one of the neural sites underlying long-term fear memories. Finally, the inactivation of the perirhinal cortex never alters retrieved fear traces, showing important differences between the amygdala, cerebellum and perirhinal cortex in emotional memories.

Reactivation with a simple exposure to the experimental environment is sufficient to induce reconsolidation requiring protein synthesis in the hippocampal CA3 region in mice

Our understanding of the memory reconsolidation process is at an earlier stage than that of consolidation. For example, it is unclear if, as for memory consolidation, reconsolidation of a memory trace necessitates protein synthesis. In fact, conflicting results appear in the literature and this discrepancy may be due to differences in the experimental reactivation procedure. Here, we addressed the question of whether protein synthesis in the CA3 hippocampal region is crucial in memory consolidation and reconsolidation of allocentric knowledge after reactivation in different experimental conditions in the Morris water maze. We showed (1) that an injection of the protein synthesis inhibitor anisomycin in the CA3 region during consolidation or after a single reactivation trial disrupted performance and (2) that protein synthesis is required even after a simple contextual reactivation without any learning trial and independently of the presence of the reinforcement. This work demonstrates that a simple exposure to the spatial environment is sufficient to reactivate the memory trace, to make it labile, and that reconsolidation of this trace requires de novo protein synthesis.

Chloramphenicol: screening and review to evaluate its potential beneficial effects in leukaemia

Chloramphenicol is an antimicrobial agent having a very broad-spectrum of activity including Gram-positive bacteria, Gram-negative bacteria and anaerobes. However the use of chloramphenicol has reduced over a period of time due to the adverse effects of causing bone marrow depression or in some cases severe aplastic anaemia. As the effects are seen on the bone marrow cell, it was intended to find out if these adverse effects could be used for the benefits in leukaemia patients, using in-vitro study on leukaemic cell lines. The study showed inhibition of growth of the leukaemia cells by chloramphenicol which was comparable to or better than daunorubicin in some cell lines. The article also discusses the other adverse effect profile of chloramphenicol compared with anticancer drugs and its potential benefit in leukaemia and in neutropenic fever.

Green bone

OBJECTIVE

To describe the unusual finding of yellow-green-colored bone during routine orbital surgery, to detail its investigation, and to demonstrate its benign nature.

METHODS

When green bone was found, specimens were sent for light and fluorescent microscopy, ultraviolet photography, and spectrophotometry.

RESULTS

Yellow-green bone was encountered in 3 patients during orbital tumor excision or orbital fracture repair procedures. The only common cause was prior use of tetracycline during adolescence. All patients had healthy white dentition. In all cases, absence of neoplasia was demonstrated histologically. The bone fluoresced with a bright yellow-green color when exposed to 365-nm ultraviolet light. Histologic analysis demonstrated fluorescence located near the haversian canals. Spectrophotometry revealed absorption at 4 wavelengths specific to tetracycline: 230, 275, 380, and 440 nm.

CONCLUSIONS

Fixation of tetracycline and ensuing fluorescence occurs mostly in areas of new bone growth and mineralization. This happens during childhood but also with bone remodeling associated with tumors or fractures. Once mineralized, teeth should therefore not be affected if tetracycline exposure occurs after ages 8 to 10 years. This paucity of external clues can lead to the surprising but innocuous surgical finding of green bone. Careful history and proper investigation can confirm its origin.

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.

Cycloheximide impairs acquisition but not extinction of cocaine self-administration

The aim of the present study was to assess the role of de novo protein synthesis in the acquisition and extinction of cocaine self-administration. In a first experiment, rats were trained to respond for intravenous cocaine infusions (0.3 mg/kg) and a protein synthesis inhibitor, cycloheximide (CHX; 3 mg/kg, s.c.) was injected immediately after each self-administration session. In a second experiment, rats were allowed to acquire cocaine self-administration and CHX was injected immediately after subsequent extinction sessions. CHX impaired the acquisition, but not extinction, of cocaine self-administration. In control experiments, CHX (3 mg/kg) blocked c-Fos protein expression after foot-shock stress and impaired the acquisition of conditioned freezing but did not inhibit spontaneous locomotor activity and sucrose drinking. Our results suggest that: i) the acquisition and extinction of cocaine-reinforced behaviour have a different molecular basis; and ii) only the former process requires de novo protein synthesis.

Symptomatic hyperlactataemia precipitated by the addition of tetracycline to combination antiretroviral therapy

Hyperlactataemia in the setting of combination antiretroviral therapy for HIV infection occurs on a spectrum ranging from common, asymptomatic laboratory abnormalities to rare, potentially life-threatening lactic acidosis. Some other medications, including the biguanides, tetracycline, and even linezolid, have rarely been reported to cause lactic acidosis. Recently, cases of lactic acidosis or hyperlactataemia have been reported in patients receiving combination antiretroviral therapy that have been precipitated by the addition of other medications-eg, metformin or ribavirin. We report a case of symptomatic hyperlactataemia in a patient on combination antiretroviral therapy that was likely precipitated by the addition of tetracycline and discuss the broader implications of other medications with the potential to cause hyperlactataemia in the setting of combination antiretroviral therapy.

Brief communication: severe hepatotoxicity of telithromycin: three case reports and literature review

BACKGROUND

Telithromycin is a ketolide antibiotic approved by the U.S. Food and Drug Administration for acute bacterial infections causing sinusitis, bronchitis, and community-acquired pneumonia.

OBJECTIVE

To describe 3 cases of severe hepatotoxicity in patients receiving telithromycin.

DESIGN

Case reports.

SETTING

A tertiary care medical center.

PATIENTS

3 previously healthy patients who had recently taken telithromycin and took no other prescription medications.

MEASUREMENTS

Serologic, histologic, and liver function tests.

RESULTS

Within a few days of receiving telithromycin, the patients presented with acute hepatitis. All had jaundice and markedly abnormal results on liver function tests. Results of viral serologic tests were negative. One patient spontaneously recovered, 1 required orthotopic liver transplantation, and 1 died. Histologic examination in the latter 2 patients showed massive hepatic necrosis.

LIMITATIONS

Two patients had some history of alcohol use. The frequency of severe telithromycin-related hepatotoxicity cannot be established with case reports.

CONCLUSIONS

Telithromycin can cause severe hepatotoxicity. Caution is advised in prescribing this drug pending additional postmarketing surveillance data.

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.

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.

Antibiotics and pregnancy

Like anybody else, pregnant women are susceptible to infections. The correct treatment of these women, however, must consider along with pathogens, the infection site and antibiotic pharmacokinetics, the fetus and possible side effects to the child. When prescribing over this special condition, the physician must remember that the prescription will affect two organism and the drug must treat the mother without affecting the fetus. Beta-lactams having a long history of use without significant deleterious effects on the fetuses still are the safest choice during pregnancy. However, considering the constant increase of multi-resistant microorganisms, the physician has been forced to use different antimicrobial agents. Usually, data regarding safety during pregnancy are very limited, which causes serious doubts during prescription. In addition, many studies regarding the safe use of antibiotics during pregnancy are inconclusive or demand more evidence. The present study is a wide revision regarding the use of antibiotics during pregnancy, considering their pharmacokinetics and the clinical experience in recent years. It also intends to assist the physician during prescription and to give information to the pharmacists to help pregnant women.

Detection and Localization of Proteinuria by Dynamic Contrast-Enhanced Magnetic Resonance Imaging Using MS325

After renal transplantation, persistent glomerular disease affecting the native kidneys typically causes albuminuria, at least for a period of time, making it difficult to determine in a noninvasive fashion whether proteinuria originates in the native kidneys or the renal allograft. To address this problem, dynamic contrast-enhanced magnetic resonance imaging (MRI) using gadolinium (Gd)-based albumin-bound blood pool contrast agent (MS325) to localize proteinuria was investigated. Glomerular proteinuria was induced in Sprague-Dawley rats by intravenous injection of puromycin aminonucleoside (PAN), whereas control rats received physiologic saline vehicle. Both groups of animals underwent a 40-min dynamic contrast-enhanced MRI using radio frequency spoiled gradient echo imaging sequence after injection of Gd-labeled MS325. Contrast uptake and clearance curves for cortex and medulla were determined from acquired MR images. Compared with controls, proteinuric rats exhibited significantly lower elimination rate constants. The use of gadopentetate dimeglumine (Gd-DTPA) as a contrast agent showed smaller and less specific differences between proteinuric and control groups. In rats with one proteinuric kidney (PAN-treated) and one normal kidney (transplanted from a normal rat), MRI using MS325 was able to differentiate between the two kidneys. The results suggest that MRI with an albumin-bound blood pool contrast agent may be a useful noninvasive way to localize proteinuria. If this technique can be successfully applied in human patients, it may allow for the localization of proteinuria after kidney transplant and thereby provide a noninvasive way to detect disease affecting the renal allograft.

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.

The genesis of epileptogenic cerebral heterotopia: clues from experimental models

The pre-natal administration of methylazoxymethanol acetate (MAM) in rats is able to induce cerebral heterotopia that share striking similarities with those observed in human periventricular nodular heterotopia, a cerebral dysgenesis frequently associated with drug-resistant focal seizures. In the present study, we investigated the mode of neurogenesis in cerebral heterotopia of MAM-treated rats, by analyzing post-natal cytoarchitectural features and time of neurogenesis using bromodeoxyuridine immunocytochemistry. The cytoarchitectural analysis demonstrated the existence, in the early post-natal period, of white matter cellular bands in close anatomical relationship with the heterotopia, which most likely serve as a reservoir of young, migrating neurons for the newly forming heterotopia. The birth dating analysis demonstrated that the period of generation of neurons within the heterotopia and adjacent white matter bands, was extended in comparison to corticogenesis in normal rat brains. In addition, it demonstrated that the heterotopia were formed through a rather precise outside-in (for cortical and periventricular heterotopia) and dorso-ventral (for intra-hippocampal heterotopia) neurogenetic pattern. We hypothesize that the MAM-induced ablation of an early wave of cortical neurons is sufficient to alter per se the migration and differentiation of subsequently generated neurons, which in turn set the base for the formation of the different types of heterotopia. On this basis, we suggest a neurogenetic scheme for MAM-induced heterotopia that can also explain the origin and intrinsic epileptogenicity of periventricular nodular heterotopia in humans.

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.

Phase I and pharmacokinetic study of KRN5500, a spicamycin derivative, for patients with advanced solid tumors

BACKGROUND

KRN5500, a novel spicamycin derivative, shows an inhibitory effect on protein synthesis. This phase I study was aimed at investigating the toxicity, maximum tolerated dose (MTD) and pharmacokinetics of this compound.

PATIENTS AND METHODS

Patients with solid tumors not amenable to standard forms of treatment were eligible. KRN5500 was administered as a 2 h intravenous infusion every 4 weeks at doses of 3, 6, 10, 15 and 21 mg/m(2). Pharmacokinetic evaluation was performed at the first cycle.

RESULTS

Eighteen patients with advanced solid tumors were enrolled. A total of 26 cycles of KRN5500 were administered. The major toxicities were nausea, vomiting, diarrhea, fatigue and a mild reversible prolongation of prothrombin time. Grade 4 pulmonary toxicity (interstitial pneumonitis) was observed in one patient at a dose level of 15 mg/m(2). Severe fatigue was observed in one patient at a dose level of 21 mg/m(2) and the duration of fatigue tended to increase with the dose of KRN5500. Nausea and vomiting were frequently observed and became prolonged with increasing dose of KRN5500. These toxicity profiles were identified as unacceptable and further dose escalation above 21 mg/m(2) was withheld. The MTD was therefore determined as 21 mg/m(2). The peak plasma concentration and the area under the concentration-time curve of KRN5500 increased proportionally to the dose, suggesting linear pharmacokinetics. No objective antitumor response was observed.

CONCLUSION

KRN5500, a structurally novel protein synthesis inhibitor, warrants further investigation to overcome these toxicity profiles and improve its efficacy.

Serotonin syndrome after concomitant treatment with linezolid and citalopram

Linezolid, a new synthetic antimicrobial, is an important weapon against methicillin-resistant Staphylococcus aureus (MRSA). Although there are reports of serotonin syndrome developing after concomitant use of linezolid and the selective serotonin reuptake inhibitor paroxitene, this report concerns a patient receiving citalopram who developed thrombocytopenia, serotonin syndrome, and lactic acidosis and died following long-term linezolid therapy.

[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.

CCI-779 Wyeth

Wyeth Research (formerly Wyeth-Ayerst Research) is developing the sirolimus (rapamycin) analog CCI-779 as a potential treatment for various cancers [320924]. By November 2001, phase III trials had been initiated [428972], [429576]. In October 2001, Raymond James predicted filing in 2003, with a potential launch in 2005 [426718]. In March 2002, CCI-779, was designated for fast-track development by the FDA for the treatment of renal cell carcinoma after failure of initial therapy [442535]; at this time phase III trials for renal cell carcinoma and phase II trials for various solid tumors were ongoing [444030]. In March 2002, Wyeth revealed that filing was anticipated for 2004/2005 [443491]. In June and August 2001, Lehman Brothers predicted sales of US $40 million ($20 million in the US) in 2003, rising to US $75 million ($38 million in the US) in 2004 [418901], [420809]. In October 2001, analysts at Raymond James expected potential sales of the product at US $250 million [426718]. In May 2002, a patent (WO-00240000) was published claiming CCI-779 to be useful for the treatment of cancers of various origins, including renal, breast, cervical, uterine, head and neck, lung, prostate, pancreatic, ovarian, colon, lymphoma and melanoma.

Chloramphenicol in the 21st century

Chloramphenicol use has declined in the UK, despite it remaining highly active against a wide range of bacteria. This article will review the activity, pharmacology, toxicology, uses and potential uses of chloramphenicol in an era of increasing antimicrobial resistance.

Continuous infusion of glucagon induces severe hyponatremia and thrombocytopenia in a premature neonate

We report on a 35-week gestation infant who developed severe hyponatremia and thrombocytopenia after continuous infusion of glucagon for the treatment of intractable hypoglycemia. Given these serious side effects,glucagon infusion should be avoided in the treatment of premature infants.hypoglycemia, glucose, small for gestational age. Hypoglycemia is commonly seen in premature infants, and the provision of a standard glucose intake is often not sufficient to maintain euglycemia. For these infants, an increase in glucose infusion to provide 4 to 8 mg/kg/min is initially recommended.1 Should this approach fail, pharmacologic agents such as corticosteroids or diazoxide are indicated.1 When the serum glucose in premature or small for gestational age infants cannot be adequately maintained, a glucagon infusion is now suggested as the best treatment approach.2,3 We report the use of glucagon infusion for the treatment of severe hypoglycemia in a premature infant. A severe hyponatremia associated with transient convulsions and thrombocytopenia was observed in the neonate after treatment. Discontinuation of the glucagon infusion resulted in prompt resolution of these abnormalities.

A possible tetracycline-risperidone-sertraline interaction in an adolescent

A 15-year-old adolescent male, with Asperger's disorder, Tourette's disorder and obsessive-compulsive disorder, on a tetracycline-risperidone-sertraline treatment regimen, had an acute exacerbation of motor and vocal tics. The increase in tics may have resulted from either a tetracycline-risperidone interaction leading to decreased levels of risperidone, or a tetracycline-sertraline interaction leading to increased levels of sertraline or the natural course of the Tourette's disorder. The sertraline dose was increased with no concomitant increase in tics, and subsequent discontinuation of tetracycline resulted in an improvement in tics, which indicates an interaction between tetracycline and risperidone. The addition of antibiotics to psychotropic medications requires close monitoring due to the potential interactions.

Differential impairment of auditory and contextual fear conditioning by protein synthesis inhibition in C57BL/6N mice

A 1-trial fear conditioning was used to investigate the temporal development of fear responses expressed as increase of freezing or heart rate and its impairment by the protein synthesis inhibitor cycloheximide (CHX) in male C57BL/6N mice. Heart rate was measured with an implanted transmitter. In the memory tests, mice were exposed to tone and context provided either as foreground or background stimulus during training. The fear responses developed differently from 0 to 24 hr after training under these 3 conditions. A single pretraining CHX injection impaired both memory forms, whereas a single posttraining CHX injection impaired tone- but not context-dependent memory, with the context provided as background stimulus. It was concluded that consolidation of tone-, foreground context-, and background context-dependent fear conditioning may be mediated by partly different neuronal or partly different biochemical pathways, or both.

Lack of evidence for systemic toxicity following topical chloramphenicol use

There has been considerable controversy regarding the safety of topical chloramphenicol in ophthalmic practice. The evidence for associated haematopoietic toxicity in idiosyncratic and dose-dependent forms was reviewed. The 7 cases of idiosyncratic haematopoietic reactions associated with topical chloramphenicol reported in the literature are refutable evidence for the existence of such a response. In Scotland, despite extensive prescription of topical chloramphenicol, the incidence of acquired aplastic anaemia was found to be low, as were associated reports of blood dyscrasias throughout the UK. The epidemiology of acquired aplastic anaemia failed to make an association with topical chloramphenicol use. High-performance liquid chromatography (minimum detection limit 1 mg/l) was used to investigate whether serum accumulation of chloramphenicol occurred after topical therapy in 40 patients. The mean dose of chloramphenicol eye drops used after 1 week of treatment was 8.0 mg, and after 2 weeks, 15.3 mg. As expected, chloramphenicol failed to accumulate to detectable levels. This supported the view that topical chloramphenicol was not a risk factor for inducing dose-related bone marrow toxicity. Calls for the abolition of treatment with topical chloramphenicol based on current data are not supported.

Zilascorb(2H), a low-toxicity protein synthesis inhibitor that exhibits signs of anticancer activity in malignant melanoma

Zilascorb(2H) is a benzaldehyde derivative giving rise to strong protein synthesis inhibition. It has shown antitumor activity against human malignant melanoma grown as xenografts in nude mice. The effect was manifest only after prolonged daily treatment and was quickly reversible when treatment was stopped. Drug-induced fever was the dose-limiting toxicity observed during clinical phase I studies of zilascorb(2H). The object of the present study was to assess antitumor activity, safety and tolerability of the drug in melanoma patients. Sixteen patients with disseminated malignant melanoma were included, all presenting with WHO performance status 0-2 and adequate organ functions. Previous chemo- or radiotherapy was accepted, while patients with known CNS metastases were excluded. Due to its low solubility and quickly reversible activity, zilascorb(2H) 1400 mg was infused by the patients twice daily through a venous access port for up to 12 weeks. Induction of tumor regression was demonstrated in one patient, who was, however, withdrawn from treatment after 2 weeks because of recurrent fever and fatigue. All the 12 patients evaluable for antitumor activity had progressive disease. Zilascorb(2H) was well tolerated, except for fever reactions and reversible liver toxicity. Most patients learned quickly how to handle a venous access port, but daily self-administration of i.v. infusions became too cumbersome to justify further patient inclusion despite the tumor regression observed. We conclude that zilascorb(2H) seems to have the potential for antitumor activity in metastatic malignant melanoma and is well tolerated. Daily self-administration of drug infusions is not desirable for long periods and zilascorb(2H) tablets have been developed. Because of its favorable toxicity profile, especially compared to other protein synthesis inhibitors, zilascorb(2H) may be particularly interesting for combinations with other anticancer drugs.

Possible association between ocular chloramphenicol and aplastic anaemia--the absolute risk is very low

AIMS

To determine whether topical ocular chloramphenicol increases the risk of aplastic anaemia and to estimate the magnitude of this risk, if any.

METHODS

Population-based prospective case-control surveillance of aplastic anaemia in a community of 4.2 million inhabitants from 1980 to 1995 (67.2 million person-years) plus case-population estimate of the risk, based on sales figures of ocular chloramphenicol in the study area during the study period.

RESULTS

One hundred and forty-five patients with aplastic anaemia and 1,226 controls were included in the analysis. Three cases (2.1%) and 5 controls (0.4%) had been exposed to ocular chloramphenicol during the relevant etiological period. The adjusted odds ratio was 3.77 (95% confidence interval, 0.84-16.90). Two cases had also been exposed to other known causes of aplastic anaemia. The incidence of aplastic anaemia among users of ocular chloramphenicol was 0.36 cases per million weeks of treatment. The incidence among non users was 0.04 cases per million weeks.

CONCLUSIONS

An association between ocular chloramphenicol and aplastic anaemia cannot be excluded. However, the risk is less than one per million treatment courses.

Bismuth-containing single-antibiotic 1-week triple therapy for Helicobacter pylori eradication

BACKGROUND

Although bismuth was both the first drug shown to alter the natural history of peptic ulcer disease and also a constituent of the first very effective eradication regimens, it has been excluded from the newer regimens, despite its safety and low cost, in favour of two antibiotics.

AIM

To asses a novel 1-week regimen consisting of bismuth, clarithromycin and a proton pump inhibitor in routine clinical practice.

METHODS

One hundred and three consecutive patients with peptic ulcer disease and antral biopsies containing Helicobacter pylori were given a 7-day course of treatment with bismuth (tripotassium dicitrato bismuthate chelate) 120 mg q.d.s., clarithromycin 500 mg t.d.s. and lansoprazole 30 mg o.d. Completeness of eradication was assessed by a l3C-urea breath test, in all except three patients, at least 4 months later.

RESULTS

Of the 100 patients who were assessed in this open treatment study 84 (84%; 95% CI: 77-91%) had a negative breath test. Minor side-effects were reported by 14% and more troublesome side-effects (nausea, vomiting, diarrhoea, hallucinations, nasty taste and body pains) were reported by 10%.

CONCLUSIONS

A 1-week course of triple therapy including bismuth, clarithromycin and a proton pump inhibitor is effective in routine clinical practice and is well tolerated.