Measuring Topological Invariants in a Polaritonic Analog of Graphene

Topological materials rely on engineering global properties of their bulk energy bands called topological invariants. These invariants, usually defined over the entire Brillouin zone, are related to the existence of protected edge states. However, for an important class of Hamiltonians corresponding to 2D lattices with time-reversal and chiral symmetry (e.g., graphene), the existence of edge states is linked to invariants that are not defined over the full 2D Brillouin zone, but on reduced 1D subspaces. Here, we demonstrate a novel scheme based on a combined real- and momentum-space measurement to directly access these 1D topological invariants in lattices of semiconductor microcavities confining exciton polaritons. We extract these invariants in arrays emulating the physics of regular and critically compressed graphene where Dirac cones have merged. Our scheme provides a direct evidence of the bulk-edge correspondence in these systems and opens the door to the exploration of more complex topological effects, e.g., involving disorder and interactions.

Dynamical Solitons and Boson Fractionalization in Cold-Atom Topological Insulators

We study the Z_{2} Bose-Hubbard model, a chain of interacting bosons the tunneling of which is dressed by a dynamical Z_{2} field. The interplay between spontaneous symmetry breaking (SSB) and topological symmetry protection gives rise to interesting fractional topological phenomena when the system is doped to certain incommensurate fillings. In particular, we hereby show how topological defects in the Z_{2} field can appear in the ground state, connecting different SSB sectors. These defects are dynamical and can travel through the lattice carrying both a topological charge and a fractional particle number. In the hardcore limit, this phenomenon can be understood through a bulk-defect correspondence. Using a pumping argument, we show that it survives also for finite interactions, demonstrating how boson fractionalization induced by topological defects can occur in strongly correlated bosonic systems. Our results indicate the possibility of observing this phenomenon, which appears for fermionic matter in solid-state and high-energy physics, using ultracold atomic systems.

HrpZ harpins from different Pseudomonas syringae pathovars differ in molecular interactions and in induction of anion channel responses in Arabidopsis thaliana suspension cells

HrpZ, a type three secretion system helper protein from the plant-pathogen Pseudomonas syringae, can be recognized by many plants as a defence elicitor. Responses of Arabidopsis thaliana suspension cells to different HrpZ variants were studied by electrophysiological methods and cell death assay. Purified HrpZ originating from a compatible pathogen P. syringae pv. tomato DC3000 (HrpZ(Pto)) and incompatible P. syringae pv. phaseolicola (HrpZ(Pph)) both promoted Arabidopsis cell death. As an early response, both HrpZ variants induced an increase in time dependent K(+) outward rectifying current. In contrast, the effects of HrpZ proteins on anion currents were different: HrpZ(Pph) had no effect, and HrpZ(Pto) induced an anion current increase. This suggests that the observed responses of the K(+) channels and anion channels resulted from different and separable interactions and that the interaction implied in anion current modulation is host-specific. HrpZ(Pto) and HrpZ(Pph) also had a different sequence preference in phage display screen for peptide-binding. These peptides presumably represent a part of a putative target protein in the host, and HrpZ proteins of different P. syringae pathovars might have different binding specificities to match the allelic variation between plant species. Supporting the idea that the peptide-binding region of HrpZ is important for interactions with host cell components, we found that a mutation in that region changed the anion channel response of Arabidopsis cells.

An early Ca2+ influx is a prerequisite to thaxtomin A-induced cell death in Arabidopsis thaliana cells

The pathogenicity of various Streptomyces scabies isolates involved in potato scab disease was correlated with the production of thaxtomin A. Since calcium is known as an essential second messenger associated with pathogen-induced plant responses and cell death, it was investigated whether thaxtomin A could induce a Ca2+ influx related to cell death and to other putative plant responses using Arabidopsis thaliana suspension cells, which is a convenient model to study plant-microbe interactions. A. thaliana cells were treated with micromolar concentrations of thaxtomin A. Cell death was quantified and ion flux variations were analysed from electrophysiological measurements with the apoaequorin Ca2+ reporter protein and by external pH measurement. Involvement of anion and calcium channels in signal transduction leading to programmed cell death was determined by using specific inhibitors. These data suggest that this toxin induces a rapid Ca2+ influx and cell death in A. thaliana cell suspensions. Moreover, these data provide strong evidence that the Ca2+ influx induced by thaxtomin A is necessary to achieve this cell death and is a prerequisite to early thaxtomin A-induced responses: anion current increase, alkalization of the external medium, and the expression of PAL1 coding for a key enzyme of the phenylpropanoid pathway.

Chemotherapy in non-selected elderly patients: Factors influencing dose-intensity and toxicity

19585

Background: Chemotherapy (CT) is the treatment of choice for most metastatic cancers. Frequent functional impairment and comorbidities in the elderly increase the risk of chemotherapy-related acute complications. The applicability of clinical trials data to the elderly population is exposed to multiple bias. Informations extracted from non-selected treated patients (pts) may be useful. Methods: A serie of consecutive elderly cancer pts (>73 years) treated over 3 years in the oncology outpatient unit, and receiving CT were included for analysis and assessed using prechemotherapy evaluation of cancer in the elderly (including performance status, comorbidities, glomerular filtration rate, liver tests, hemogram, nutritional status, inflammation tests). Relationship between preCT evaluation and acute complications, unscheduled hospitalisation, mortality were investigated by univariate analyses. Comparison between planned and realised dose- intensity of CT protocols could be extracted for the CT prescription software. Results: 108 pts with a median age of 78 years (73- 89; 44% over 80) were identified. Characteristics included performance status (PS) ≥ 2 (44%), chronic renal insufficiency (47%) ; ≥2 comorbidities (75%). Primary tumour was urologic (31%), gastro-intestinal (29%), mammary and gynaecologic (20%); pulmonary (16%) or other (4%). Disease stage was metastatic for 82% of pts. Most CT regimens contained a platinum derivative (55%), gemcitabine (25%), 5-FU (20%), taxanes (17%), vinorelbine (15%). Transfusion requirements were higher in PS≥2 pts (p<0.0001). Febrile neutropenia correlated with PS, lymphocytopenia and PINI =(CRP×AAG)/(albumin×pre-albumin)>10 (p<0. 05). Unscheduled hospitalisation correlated with PS, lymphocytopenia, PINI, more than 2 co-morbidities, more than 4 co-medications. Oxaliplatin- and paclitaxel-containing CT protocols were associated with significant reduction of dose-intensity because of reduced number of cycles due to neurosensory toxicity (p=0.01). Conclusions: Lymphocytopenia, PS, and PINI were the most relevant prognosticators of short-term CT outcome. Elderly pts characteristics are associated with higher risk of acute toxicity and increased sensitivity to neurosensory cumulative toxicity.

No significant financial relationships to disclose.

Mutations in the SPG3A gene encoding the GTPase atlastin interfere with vesicle trafficking in the ER/Golgi interface and Golgi morphogenesis

Mutations in SPG3A causing autosomal dominant pure spastic paraplegia led to identification of atlastin, a new dynamin-like large GTPase. Atlastin is localized in the endoplasmic reticulum, the Golgi, neurites and growth cones and has been implicated in neurite outgrowth. To investigate whether it exerts its activity in the early secretory system, we expressed normal and mutant atlastin in cell culture. Pathogenic mutations in the GTPase domain interfered with the maturation of Golgi complexes by preventing the budding of vesicles from the endoplasmic reticulum, whereas mutations in other regions of the protein disrupted fission of endoplasmic reticulum-derived vesicles or their migration to their Golgi target. Atlastin, therefore, plays a role in vesicle trafficking in the ER/Golgi interface. Furthermore, atlastin partially co-localized with proteins of the p24/emp/gp25L family that regulate vesicle budding and trafficking in the early secretory pathway, and co-immunoprecipitated p24, suggesting a functional relationship that should be further explored.

Fungal hypaphorine reduces growth and induces cytosolic calcium increase in root hairs of Eucalyptus globulus

Root hairs are tubular cells resulting from a tip-localized growth in which calcium ions play a key role. Hypaphorine, an indole alkaloid secreted by the fungus Pisolithus microcarpus during the formation of ectomycorrhizae with the host plant Eucalyptus globulus, inhibits root hair tip growth. Hypaphorine-induced inhibition is linked to a transient depolarization of the plasma membrane and a reorganization of the actin and microtubule cytoskeletons. Here we investigated the activity of hypaphorine on calcium distribution in E. globulus root hairs with the ratiometric fluorochrome calcium indicator Indo-1. In 85% of actively growing root hairs, a significant but modest calcium gradient between the apex and the base was observed due to an elevated cytoplasmic calcium concentration at the apical tip. Following exposure to 1 mM hypaphorine, the apical and basal cytoplasmic Ca(2+) concentration increased in 70 and 77% of the hairs, respectively, 10 min after treatment. This led to a reduced calcium gradient in 81% of the cells. The hypothetical links between calcium concentration elevation, regulation of actin cytoskeleton dynamics, and root hair growth inhibition in response to hypaphorine treatment are discussed.

Actin organization during eucalyptus root hair development and its response to fungal hypaphorine

The fungus Pisolithus microcarpus establishes an ectomycorrhiza with Eucalyptus globulus. This symbiosis involves a fungal synthesis and secretion of hypaphorine, an indolic compound. Previous studies have shown that hypaphorine induces an alteration in the actin cytoskeleton of elongating root hairs and inhibits hair elongation. Using an alternative approved method, we analyzed the effects of hypaphorine on the E. globulus root hair cyto-architecture and actin configuration in more detail and provide new results. One mM hypaphorine stops root hair elongation within 20 min, and changes the hair cyto-architecture. Semi-quantitative analysis of the actin cytoskeleton before and after treatment with hypaphorine shows that hypaphorine induces a shift from fine F-actin to F-actin bundles in the sub-apex of the hair, which occurs first in the mid-plane of the cell. This creates a sub-apical cell centre free of filamentous actin, an actin configuration that differs from that during developmental growth arrest. The mechanism of action of hypaphorine is discussed.

[Parkinson's disease, progressive lumbar kyphosis and focal paraspinal myositis]

INTRODUCTION

The camptocormia (bent spine) is characterized by a severe forward flexion of the thoracolumbar spine which disappears in the supine position. Clinical case. We describe a typical case observed in a parkinsonian patient. The MRI, electromyogram and biopsy of the paraspinal muscles revealed a typical myositis pattern.

DISCUSSION

This case, the sixth published to our knowledge, confirms that focal myositis is associated with the camptocormia in Parkinson's disease. Typically it is observed in male subjects, appearing 4 to 6 years after the onset of Parkinson's disease, in fluctuating patients treated by an association of L-Dopa and agonist. It appears quickly and becomes the most important symptom. Antiparkinsonian drugs are useless.

CONCLUSION

This exceptional picture raises original pathophysiological and therapeutic questions. Systematic studies should be performed in order to detail the pathophysiological link between these 3 entities: Parkinson's disease, focal myositis and camptocormia.

[Laennec Hospital]

When the Laennec Hospital of Paris closed, after 366 years of activities for the patients, the articles about the circumstances of the foundation and the main stapes of the institution which became an very famous university hospital it present the available information of the history of the apothecaries, of the "gagnants-maitrise", pharmacists and the pharmacy's interns who succeeded themselves to create and dispense the medicaments necessary to the patients hospitalized or welcomed in ambulatory. It describes the evolution of the places, of the material, of forms, of the organization, of the medicaments and of the missions of what became the Pharmacy department after the recent individualization of the biological analysis in the biochemistry.

Heart rate response to two lifting techniques

OBJECTIVE

To determine the heart rate response to repetitive lifting of light weights employing two techniques, stoop and squat.

DESIGN

Randomized cross-over trial.

PARTICIPANTS

Twenty healthy volunteers (11 women, 9 men), mean age of 25 years, recruited from the staff of a physical medicine and rehabilitation department.

METHODS

Subjects lifted and lowered a box weighing 0, 1, or 3 kg, using the stoop (bent at waist with knees straight) and squat (knees bent) techniques, 20 times in 1 minute.

MAIN OUTCOME MEASURES

The heart rate was recorded every 5 seconds during the effort aid 30 seconds and 1 minute after the test.

RESULTS

Significantly higher heart rates were found during both the test and recuperation phases of the squat technique with each of the three loads (p < .05). The heart rate increase was also higher with the 3 kg load than with the 1 kg or 0 kg load (p = .0001).

CONCLUSION

The heart rate is lower using the stoop technique for lifting. This may explain why individuals choose the more ergonomically risky stoop technique in everyday lifting tasks.

Relevance of urinalysis monitoring of methadone maintenance patients: a clinical-biological agreement on 41 patients

Abstract This study evaluated the concordance of concomitant urinalysis and clinical assessments of drug abusers included in a methadone maintenance programme. The agreement between a clinical subjective score and an objective biological score, both measuring the evolution of illicit substance consumption over 12 months, was analysed. The clinical score, established by physicians and applied during patient interviews, was determined at entry into the programme and re-evaluated after 6 and 12 months. Forty-one patients were evaluated. The urinalysis score was based on regular screening of urine samples with the EMIT method. Agreement between the two scores was determined by using the kappa coefficient for each substance (opiates, benzodiazepines and cocaine) for each time-point. The calculated kappa coefficients showed poor agreement between the two scores, but could indicate the complementarity of these clinical and biological appraisals. Indeed, the urinalysis objectively detected change in drug use before the clinician. Thus, urinalysis monitoring should be considered as an additional and complementary biological procedure for patient follow-up by physicians.

[Safety of oxygen-pressure-reducing valves]

When a gas cylinder valve is opened slowly, as required, the associated pressure reducing valve works properly and gas expansion decreases the temperature of the device proportionally to the delivered gas flow. Conversely, when the valve is opened rapidly, the pressure in the high pressure chamber grows suddenly from 0 to 200 bars in the case of a full O2-cylinder, if no flow is required at the valve outlet. This adiabatic compression in a small space generates a peak of high temperature. In the presence of combustible foreign debris and O2, ignition can occur. When the melting point of the metallic component is reached the device bursts and those in the vicinity are at risk of burns or death from inhalation of melten metallic debris. As several of such critical incidents occurred with O2-pressure-reducing valves whose high pressure chambers were made of aluminium, the French medical devices agency has enacted a regulation prohibiting their use.

A comparison of thoracic and lumbar epidural techniques for post-thoracoabdominal esophagectomy analgesia

PURPOSE

To compare thoracic epidural analgesia (TEA) using a bupivacaine/fentanyl mixture and lumbar epidural analgesia (LEA) with morphine, in respect to the time to extubation and the quality of post-operative analgesia, in patients having thoracoabdominal esophagectomy.

METHODS

Twenty two patients scheduled for elective thoracoabdominal esophagectomy were randomized to TEA or LEA. Postoperatively, the TEA group received Patient Controlled Epidural Analgesia (PCEA) with bupivacaine 0.125% and 5 microg x ml(BI) fentanyl, and the LEA group received PCEA with 0.2 microg x ml(BI) morphine. A blinded observer assessed criteria for tracheal extubation and the time of tracheal extubation was recorded. Early extubation was defined as tracheal extubation within four hours postoperatively. Visual analogue pain scores at rest (Static Visual Analogue Pain Scores, SVAPS) and with movement (Dynamic Visual Analogue Pain Scores, DVAPS) were recorded at 1, 6, 12, 18 and 24 hr post-extubation. Failure of the epidural protocol (FEP) was defined as a request for additional analgesia.

RESULTS

Tracheal extubation was achieved in 70% of the LEA and 100% of the TEA at four hours postoperatively (P=NS). However, the TEA group achieved earlier extubation times when assessed with log rank testing (P = 0.01). By six hours post-extubation FEP had occurred in 50% of the LEA group but in none of the TEA group (P = 0.01). Mean SVAPS and DVAPS were lower in the TEA than in the LEA group at all measured times (P < 0.01).

CONCLUSION

This study has demonstrated superior pain control in patients undergoing thoraco-abdominal esophagectomy treated with TEA than with LEA, particularly for pain with movement. Tracheal extubation occurred earlier in the TEA group, but this difference was not significant at four hours postoperatively.

Comparative study of continuous extrapleural intercostal nerve block and lumbar epidural morphine in post-thoracotomy pain

OBJECTIVES

To compare the efficacy of continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine and continuous lumbar epidural block with morphine in controlling post-thoracotomy pain and to measure serum bupivacaine concentrations during extrapleural infusion.

DESIGN

A prospective, randomized, controlled trial.

SETTING

St. Joseph's Hospital, Hamilton, Ont., a tertiary care teaching centre.

PATIENTS

Sixty-one patients booked for elective thoracotomy were randomized by scaled envelope to two groups.

INTERVENTIONS

Group A received a continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine as a bolus of 0.3 mL/kg followed by an infusion of 0.1 mL/kg every hour for 72 hours. Group B received a continuous lumbar epidural block with morphine as a bolus of 70 g/kg followed by an infusion of 7 g/kg every hour for 72 hours.

MAIN OUTCOME MEASURES

Pain was assessed by a linear visual analogue scale (VAS) pain score. The cumulative amount of "rescue" intravenous morphine used, and serum bupivacaine concentrations were measured as secondary outcomes.

RESULTS

Pain control was the same in both groups as assessed by linear VAS score (p = 0.33). The cumulative dose of intravenous morphine for supplemental analgesia was statistically significant between the groups: group A patients used more morphine than group B (p < 0.05). Accumulation of serum bupivacaine was present with no clinical toxicity.

CONCLUSIONS

There is no significant difference in the degree of post-thoracotomy pain control measured by the VAS score when analgesia is provided by continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine or lumbar epidural block with morphine. Larger amounts of rescue analgesia were used by patients in the continuous extrapleural group with bupivacaine than those in the continuous lumbar epidural block with morphine. Serum bupivacaine concentrations rise without clinical toxicity.

Comparison of general anesthesia with and without lumbar epidural for total hip arthroplasty: effects of epidural block on hip arthroplasty

STUDY OBJECTIVES

To determine whether lumbar epidural anesthesia, when combined with general anesthesia, decreases perioperative blood loss, the incidence of postoperative deep vein thrombosis (DVT), cardiac dysrhythmias, and ischemia in patients undergoing total hip arthroplasty (THA).

DESIGN

Randomized, controlled study.

SETTING

A university hospital.

PATIENTS

37 ASA physical status I, II, and III patients, undergoing elective THA.

INTERVENTION

Patients were divided into two statistically comparable groups: Group GA = general anesthesia; Group CEGA = general anesthesia plus lumbar epidural anesthesia. All patients had 48-hour perioperative Holter monitoring, applied on admission, the day prior to surgery. In both groups, general anesthesia was induced with thiopental sodium and muscle relaxant, and maintained with oxygen, nitrous oxide, isoflurane, opioid, and muscle relaxant. Group B received lumbar epidural anesthesia with 10 ml 0.5% bupivacaine with 1:200,000 epinephrine prior to anesthesia induction. Blood loss was measured by suction bottle contents, sponge weights, and collection drainage. DVT was assessed with postoperative leg scanning, plethysmography, and venogram.

MEASUREMENTS AND MAIN RESULTS

Intraoperative blood loss was less after combined epidural-general anesthesia (663.8 ml +/- 299.0 ml) than after general anesthesia alone (1,259.2 ml +/- 366.0 ml). The difference was found to be statistically significant (p < 0.00005). No difference was found between the two groups in postoperative blood loss, incidence of DVT, cardiac dysrhythmias, or ischemia.

CONCLUSION

Combined regional-general anesthesia decreases intraoperative blood loss in THA, and thereby offers an advantage over general anesthesia alone.

Serum bupivacaine concentrations during continuous extrapleural infusion

PURPOSE

To determine the rate of increase in serum bupivacaine concentration during continuous extrapleural infusion.

METHODS

After thoracotomy for lobectomy under general anaesthesia, nine patients had an extrapleural catheter inserted, before chest closure, in a costovertebral gutter constructed surgically by lifting the parietal pleural. Bupivacaine 0.5% with epinephrine 1:200.000 was injected through the catheter as 0.3 ml.kg-1 bolus followed by 0.1 ml.kg-1.hr-1 for five days. Serum bupivacaine (free and total), albumin, alpha-1 acid glycoprotein concentrations were measured 15 min after injection and at 24 hr intervals for five days. Bupivacaine concentrations were determined by column liquid chromatography using solid phase extraction. Serum alpha-1 acid glycoprotein concentration was determined by nephelometry on QM 300 protein analyzer. Serum albumin concentration was determined by bromocresol green dye binding procedure on Hitachi 717 Autoanalyzer.

RESULTS

A continuous elevation in total serum bupivacaine was observed, with an average value of 0.75 microgram.ml-1 on day 1 to 2.77 micrograms.ml-1 on day 4 (P < 0.05). There was no increase in postoperative free serum bupivacaine concentration; average value of 177 pcg.ml-1 on day 1 and 249 pcg.ml-1 on day 4 (P = 0.92). Postoperative serum alpha-1 acid glycoprotein concentration showed a steady rise with an average value of 0.94 microgram.ml-1 on day 1 and 1.47 micrograms.ml-1 on day 4 (P < 0.05). No change was observed in post-operative serum albumin with an average value of 31.4 g.l-1 on day 1 and 31.3 g.l-1 on day 4.

CONCLUSION

Continuous extrapleural infusion of bupivacaine over five days after thoracotomy is associated with a steady increase in total serum bupivacaine concentration and no elevation in free serum bupivacaine concentration.

Column liquid chromatographic determination of bupivacaine in human serum using solid-phase extraction

A convenient and economical procedure for the extraction of bupivacaine and its major metabolites, desbutylbupivacaine and 4'-hydroxybupivacaine, from serum is described. A 0.25-ml aliquot of 4 micrograms/ml solution of N-pentyl-2,6-pipecoloxylidide used as the internal standard and an equal volume of the serum sample are applied to a 1-ml BondElut C18 silica extraction column which has been conditioned by subsequent washing once with 1 M HCl, twice with methanol and once with water. After passing the sample at a slow rate, the column is washed twice with water and once with acetonitrile. The desired compounds are then eluted with a 0.25-ml aliquot of a mixture of 35% perchloric acid-methanol (1:40, v/v). A 5-microliters aliquot of the eluate is injected onto a 150 x 4.6 mm I.D. column packed with 5-microns C8 silica particles, which is eluted at ambient temperature with a mobile phase of acetonitrile-10 mM KH2PO4 (25:80, v/v) at a flow-rate of 1.5 ml/min. The peaks are detected at 205 nm. The extraction recovery of all the compounds is in the range of 90%. The chromatogram is clean and the desired peaks are well separated from each other and from the extraneous peaks.

[Treatment of sexual impotency by intra-cavernous injections of prostaglandin E1. Report of 180 patients]

As already reported, PGE1 induces a valid erection, when administered intracavernously, without causing prolonged erection or general side effects. We have tested PGE1 (< 20 micrograms) in 180 patients suffering from organic erectile impotence, a complete erection was observed in 130 (72.2%), while incomplete erection was noted in 37 (20.5%). In both groups (92.7%) erection was sufficient for sexual intercourse. Among the best results, 41 patients had previously received high doses intracavernous injection of papaverine, without any benefit, and 15 patients have cavernosal venous leakage documented by cavernosometry and cavernosography before prostaglandin E1 test. Tumescence without rigidity was noted in 13 (7.2%). Of these 167 patients, 95 entered an autoinjection protocol for treatment of erectile dysfunction, using special device. In our series neither systemic reaction nor prolonged erection occurred. No fibrosis of cavernous tissue or scar formation was observed after up to 125 injections. However, 19 patients (10.5%) reported burning sensations during the entire period of erection and one patient (0.5%) had an haematoma at the site of the injection. PGE1 is effective in inducing artificial penile erection and it has a role in the diagnosis and treatment of erectile dysfunction, it is considered to be a more suitable agent than other vasoactive drugs.

Comparison of serum hydroquinidine determination by fluorescence polarization immunoassay and liquid chromatography

Hydroquinidine is a structural analogue of quinidine. It is used in the treatment and prevention of cardiac arrhythmias and necessitates serum monitoring. Fluorescence polarization immunoassay (FPIA) of quinidine has been proposed and we have tested the performance of this assay for hydroquinidine using its cross-reaction with quinidine. Tracer (quinidine labelled with fluorescein) and anti-serum were purchased from Abbott S.A. Standard curves were obtained using specifically prepared hydroquinidine calibrators and within-run and run-to-run precision values (expressed as relative standard deviation) (RSD) lower than 5.3% (n = 10). In order to evaluate specificity of this assay in the clinical situation, FPIA and liquid chromatography results were compared.

Quantitative liquid chromatography of allopurinol and oxypurinol in human plasma and urine

A high performance liquid chromatographic (HPLC) assay is described for allopurinol and oxypurinol determination in human plasma and urine, in the range expected during therapy. The procedure involves addition of trichloroacetic acid to samples, followed by centrifugation. The supernatant is then neutralized and analyzed by reversed-phase HPLC. Characteristics of the method are reported, and data are presented on its application to the pharmacokinetics studies. Separation is optimal with an octadecylsilane (ODS) stationary phase and a sodium acetate mobile phase adjusted to pH 7.2 for plasma and pH 5 for urine.

[Prevention of postoperative anaerobic bacterial infections in abdominal surgery with metronidazole suppositories]

Metronidazole is widely used for the prevention and treatment of post-operative anaerobic infections. In this study, the prophylactic effectiveness of metronidazole suppositories was tested in patients undergoing abdominal surgery. The suppositories had previously been tested in healthy subjects for drug absorption and tolerance. Patients were divided into three treatment groups: one group received the drug intravenously, another as suppositories and the third one by both routes. Clinical effectiveness was evaluated and plasma metronidazole levels were measured. On the basis of the results obtained, we suggest that a 1 g suppository should be administered 8-hourly over the 20 hours preceding surgery, then 12-hourly if preparation of the digestive tract can be inserted between two administrations. In emergency surgery, 1 suppository must be given at least 1 hour before induction, the 12-hourly, and a 500 mg intravenous infusion at the time of induction.

[Prevention of postoperative anaerobic infections. Economic significance of metronidazole suppositories]

Metronidazole is widely used in the preventive and curative treatment of post-operative anaerobic infections. As the intravenous form is very expensive, a 1 g suppository has been developed. The pharmacokinetics of metronidazole injection and suppository was studied comparatively in 10 healthy subjects. The serum bioavailability of the rectal form was 80% with a peak serum concentration of 10 mg/l four hours after dosing. From calculated pharmacokinetic values it may be suggested that: (1) in cases of elective surgery treatment could begin with the rectal form alone at the rate of one suppository 12-hourly, starting 48 hours before surgery; (2) in emergency surgery, 0,5g of metronidazole i.v. over 20 minutes and a 1 g suppository should be administered at the time of premedication, treatment being continued with one suppository 12-hourly; (3) in patients at high risk of anaerobic infection, one suppository should be given 8-hourly, starting 24 hours before surgery. The main advantage of the rectal treatment is that it is much cheaper than the intravenous treatment administered during the same period.

Liquid chromatography determination of thiopentone in human plasma

A rapid microprocedure for the liquid chromatographic analysis of thiopentone in plasma is described. Reversed-phase liquid chromatography was performed on a microparticulate C18 column using as a mixture of 60% methanol/40% water as mobile phase and ultraviolet detection (290 nm). The method used carbamazepine as internal standard and ethyl acetate as extraction solvent. The analytical recovery was 95%; the reproducibility, 6.5%; and the sensitivity limit of detection, 0.2 mg/liter. The method has been used in preliminary studies to determine the plasma concentrations in patients receiving thiopentone by the intravenous route. A method using direct injection is described.