A pharmacokinetic interpretation of increasing concentrations of DEHP in haemodialysed patients

The degree of exposure to DEHP was assessed in 11 patients with chronic renal failure undergoing maintenance haemodialysis. The amount of DEHP leached from the dialyser during a 4-h dialysis session was estimated by monitoring the DEHP blood concentration using a HPLC method. When a patient undergoes a dialysis treatment, the concentration of di-2-ethylhexyl phthalate (DEHP) in venous blood is increased when the blood crosses through the dialysis apparatus. This increase may be explained either because DEHP is not extracted by the dialyser or because DEHP comes from the dialysis bath due to contact of blood against plasticized pipes. To explain the increasing concentration of DEHP during treatment of renal failure using plasticized tubing, we propose a pharmacokinetic compartmental model in order to fit raw data obtained from dialysed patients and to get the amount of DEHP which enters the body by AUC calculations. Results obtained after HPLC analysis show a high degree of interpatient variability in DEHP retained. This amount can reach a toxicity level because of repetitive dialysis treatments over prolonged periods of time. In the coming years, it seems necessary to reconsider the use of DEHP as a plasticizer in medical devices. Highly unacceptable amounts of DEHP leached during the dialysis session could be easily avoided by careful selection of haemodialysis tubing.

Neurosedative and antioxidant activities of phenylpropanoids from ballota nigra

Ballota nigra is a European plant known for its neurosedative properties. In this study, the ability of five phenylpropanoids (verbascoside, forsythoside B, arenarioside, ballotetroside, and caffeoyl malic acid) isolated from a hydroalcoholic extract, to bind to benzodiazepine, dopaminergic, and morphinic receptors was investigated. To carry out these studies, affinity tests with rat striata, entire brains and receptor rich preparations were employed. In addition, the phenolic aspect of these five phenylpropanoid esters led to investigate antioxidant activities using cell-free experiments and cellular experiments including isolated polymorphonuclear neutrophils (PMN). Effects of phenylpropanoid esters against reactive oxygen species as superoxide anion, peroxide hydrogen, hypochlorous acid and hydroxyl radical were tested. These molecules are liberated by PMN during inflammatory disorders, so that reproduction of this process in vitro stimulating PMN by chemical stimulants was undertaken. Results show that four of the five compounds are able to bind to the studied receptors. Inhibitory concentrations at 50% were determined and vary from 0.4 to 4.7 mg/ml. This may be in relation with the Ballota nigra known neurosedative activities. Results concerning antioxidant investigations evidence an ability to scavenge reactive oxygen species. Inhibitory concentrations at 50% obtained are comparable to those of known antioxidant drugs (mesna or N-acetyl cysteine). Moreover, the use of different stimuli having various pathways of action on PMN oxidative metabolism permits to establish that each phenylpropanoid ester has its own particular way of action by using proteine kinase C or phospholipase C pathways.

Long term results of lateral pancreaticojejunostomy for chronic alcoholic pancreatitis

OBJECTIVE

To assess our long term results of lateral pancreaticojejunostomy in patients with alcoholic pancreatitis.

DESIGN

Retrospective study.

SETTING

University hospital, France.

SUBJECTS

57 patients (48 men, 9 women, mean (SD) age 46 (7) years who required surgical treatment of chronic alcoholic pancreatitis between January 1977 and October 1995.

INTERVENTIONS

Lateral pancreaticojejunostomy with or without another procedure. Outcome classified as excellent, good, fair, or poor.

MAIN OUTCOME MEASURES

Postoperative morbidity and mortality; relief of pain; reduction in use of analgesics and exocrine supplements; effect on exocrine and endocrine insufficiency; and return to paid work.

RESULTS

There were no postoperative deaths and no pancreatic fistulae, but there were 17 other postoperative complications (30%). Median follow up was 65 months (range 8-206), during which 12 patients died (21%). Result was judged excellent in 16 (28%), good in 27 (47%), fair in 5 (9%), and poor in 9 (16%). Pain control was significantly improved, analgesic usage decreased, less pancreatic enzyme supplementation was required, and 25 patients returned to paid work (p = 0.0001 in each case). Exocrine and endocrine function remained stable. The results were better if the patient gave up misusing alcohol (p = 0.03) and if the operation was done within 4 years of the development of pancreatitis (p = 0.03).

CONCLUSIONS

Lateral pancreaticojejunostomy is a safe procedure that can improve functional outcome in patients with chronic alcoholic pancreatitis, and does not worsen pancreatic function.

Immune reconstitution and outcome after unrelated cord blood transplantation: a single paediatric institution experience

We report the outcome of 12 children who underwent unrelated cord blood transplant (U-CBT) in a single institution between February 1997 and July 1998. The 1 year event-free survival was 67% (95% CI of 26%). Four children died with infectious complication as cause of death in three cases. Immune reconstitution was studied during first year post transplant by assaying total lymphocyte counts, B cells, NK cells and T cell subsets in the eight disease-free surviving patients. We observed a prompt recovery of CD19+ cell number which was greater than 500/microl at 9 months for all patients except the one with severe cGVHD. B cells constituted the predominant lymphocyte subset at 6 and 9 months post transplant with normal or elevated B cell numbers according to normal paediatric range. We noted normal serum immunoglobulin levels at 6 months post transplant for IgA and IgM and at 9 months for IgG. The CD3+ cell count and particularly the CD3+CD8+ T cell subset remained depressed until 12 months post transplant. Six months after unrelated CBT, seven out of eight patients had less than 100 CD3+CD8+ cells/microl. CD3+CD4+ cell recovery was less impaired with all children achieving an absolute count of CD3+CD4+ cells greater than 200/microl during the first year in a median of 5 months. The percentage of NK cells was elevated during the first 6 months after CBT but their absolute count remained within the normal range. Bone Marrow Transplantation (2000) 25, 53-57.

Effects of two antihypertensive agents, labetalol and metoprolol, on the production of reactive oxygen species by normal polymorphonuclear leukocytes in vitro

OBJECTIVE

Increased lipid peroxidation is a putative causal factor for preeclampsia. Because oxygen free radicals are involved in inducing the lipid oxidation chain reaction, we evaluated two beta adrenoreceptor blockers, labetalol and metoprolol, currently used for treating hypertension with regard to their ability to inhibit the formation of reactive oxygen species during respiratory burst of human normal polymorphonuclear leukocytes in vitro.

METHODS

We determined whether labetalol or metoprolol have antioxidative activity in a model of polymorphonuclear leukocytes stimulated in vitro with phorbol-12-myristate-13-acetate (PMA) and N-formyl-methionin-leucin-phenylalanin (fMLP). We also studied the scavenging properties of these two drugs using acellular systems.

RESULTS

Labetalol inhibits O2-. production by neutrophils activated by fMLP (IC50 = 17.5 mg/L) and weakly by PMA (43.6% inhibition at 100 mg/L). It also possesses a significant activity on OH. production (IC50 = 65 mg/L) that may depend in part on its ability to interfere with iron in the Fenton reaction. The same assays performed with metoprolol did not show any inhibitory effect on O2.- generation. It decreased weak OH. production by neutrophils, as a result of cellular and scavenging effects.

CONCLUSION

Labetalol shows important antioxidative properties in vitro with regard to normal leukocyte oxidative metabolism.

Stability, compatibility and plasticizer extraction of quinine injection added to infusion solutions and stored in polyvinyl chloride (PVC) containers

The stability of quinine was determined in various diluents and in polyvinyl chloride (PVC) containers. The release of diethyhexyl phthalate (DEHP) from PVC bags into intravenous infusions of quinine was also measured. We used an injection of two doses of quinine; quiniforme at 500 mg and quinimax at 400 mg in either 250- or 500-ml PVC infusion bags containing 5% dextrose, to give initial nominal concentrations of 2 or 1 mg ml(-1) quiniforme and 1.6 or 0.8 mg ml(-1) quinimax, the mean concentrations commonly used in clinical practice. Samples were assayed by stability-indicating high-performance liquid chromatography (HPLC) and the clarity was determined visually. Experiments were conducted to determine whether the stability and compatibility of quinine would be compromised, and whether DEHP would be leached from PVC bags and PVC administration sets during storage and simulated infusion. There was no substantial loss of quiniforme and quinimax over 1- or 2-h simulated infusion irrespective of the diluent, and storage during 8 h at 22 degrees C, 48 or 72 h at 4 degrees C and 96 h at 45 degrees C. Leaching of DEHP was also detected during simulated infusion delivery using PVC bags and PVC administration sets. The quantity was less than 2 microg ml(-1). During storage at 4 degrees C and room temperature the leaching of DEHP was low, but when the temperature was 45 degrees C the quantity was high, 21 microg ml(-1). To minimise patient exposure to DEHP, quinine solutions with all drugs should be infused immediately or stored for a maximum of 48 h at 4 degrees C.

Antioxidant properties of albumin: effect on oxidative metabolism of human neutrophil granulocytes

The present study aims at investigating the effect of bovine serum albumin (BSA) on the trial of oxidative-stress. The antioxidant effects of BSA were determined by human neutrophil granulocytes oxygen free radicals and their by-products (O2-, H2O2, HOCl) productions. BSA interacts with those reactive oxygen species (ROS) in a dose-dependent manner. The 50% inhibitory concentration (IC50) of BSA estimated, after phorbol-12-myristate-13-acetate (PMA) stimulation were: 33.5 mg/ml for O2-, 6.5 mg/ml for H2O2, and 6.85 mg/ml for HOCl. When neutrophils were washed after pre-incubation with BSA, there was no significant decrease of ROS after stimulation of PMA (maximal: 15 +/- 1.2%). In the free cell experiments, IC50 for H2O2 and HOCl were 7.86 mg/ml and 0.67 mg/ml, respectively. The mechanism at which BSA acts may result from a simple chemical interaction with ROS rather than an intracellular mechanism by intervention in PMA oxidative metabolism. These antioxidant activities confer to BSA properties, which might be used to prevent damage inflicted by these ROS during inflammatory disorders.

Serum opioid activity after physical exercise in rats

In order to study the effect of exercise on the total serum opioid activity, female rats were trained for 3 weeks on a motor-driven treadmill and the experiment was ended by a final strenuous run until exhaustion. The serum samples were taken immediately after the final run and were analyzed by radioreceptor assay. Despite considerable interindividual variations, serum opioid activity, expressed in met-enkephalin equivalents (ME eq +/- S.D.), was significantly higher in the exercising group (74.5+/-50.5 pmol ME eq/ml) than in the control group (35.7+/-20.2 pmol ME eq/ml). Because of the much lower molar levels of beta endorphin and met-enkephalin, this result suggests that many other opioid peptides might be involved in that increase.

Evaluation of the effects of Gd complexes used as magnetic resonance imaging contrast agents, on superoxide dismutase: comparison of two methods

Investigations are currently being made into the safety of gadolinium complex contrast agents used in Magnetic Resonance Imaging. Their hyperosmolality or potential Gd3+ release is evoked as a cause of various anaphylactoid reactions to be observed in humans after intravenous injection. An estimation has already been made of their effects on the liberation of reactive oxygen intermediates by neutrophils. The purpose of this study was to find a suitable method to measure SOD activity in the presence of these hyperosmolar solutions, and to evaluate their action on this activity. Two techniques were compared to measure this activity. Results and statistical analysis showed that pyrogallol autoxidation was greatly affected by solution osmolalities, whereas ferricytochrome C reduction was not. Gadopentetate dimeglumine and gadoterate meglumine seemed to activate Cu, Zn SOD in vitro, but did not exhibit any SOD-like activity. Gadodiamide did not interfere with this system of detoxication.

Omeprazole-induced leukopenia. A case report

BACKGROUND

Omeprazole has been marketed in France since 1989, for the healing of peptic ulcers, erosive reflux oesophagitis, and the Zollinger-Ellison syndrome. However, the drug has been associated with serious adverse reactions, including haemolytic anaemia and acute interstitial nephritis. More recently, an autoimmune syndrome induced by omeprazole has been described.

OBJECTIVE

We present here a clinical history and an in vitro test of cytotoxicity linking leukopenia to omeprazole.

RESULTS

A 37-year-old woman was hospitalized in the intensive care unit of our hospital with acute pulmonary insufficiency secondary to pneumonia. 72 h after starting omeprazole treatment, a decrease in leucocyte count was observed. The leukopenia was maximal on day 22: total white cell count was 2. 1x109/l, and neutrophil count was less than 0.75x109/l. In order to find the cause of this leukopenia, an in vitro cytotoxicity test was performed. The test was positive only when patient neutrophils and patient serum were in the presence of omeprazole. This cytotoxicity seems to be complement-dependent, as in the presence of heated serum, the omeprazole toxic effect was substantially reduced.

CONCLUSION

This case report suggests that the leukopenia was associated with omeprazole.

Compatibility study of 5-fluorouracil with PVC bags after repackaging into two types of infusion admixtures

The stability and compatibility of 5-fluorouracil (5-FU) in admixtures for continuous intravenous infusion using PVC bags and administration sets were studied. 5-fluorouracil was reconstituted and diluted to 1.8 mg/ml for infusion in polyvinyl chloride and glass containers, and to 1 mg/ml to 16 mg/ml for storage in polyvinyl chloride bags containing 5 per cent dextrose or 0.9 per cent sodium chloride injections. Admixtures were stored at +4 degrees C and with protection from light, for 7 days. Analyses were performed by HPLC. No significant drug loss was observed during simulated infusions using PVC infusion bags and administration sets vs glass bottles and administration sets, over an infusion period used in hospitals (24 h). The solution stored at +4 degrees C with protection from light in PVC bags showed that at 1 mg/ml to 16 mg/ml, 5-fluorouracil was stable at least for 7 days in 0.9 per cent sodium chloride and 5 per cent dextrose.

In vitro effects of spiramycin and dirithromycin on IL1 beta production by human LPS-stimulated mononuclear cells

Polymorphonuclear neutrophils are the predominant cells in acute inflammatory lesions and their functions and recruitment are regulated by cytokines, including IL1, TNF and IL8. Antibiotic modulation of inflammatory effects has stimulated investigations of antibiotics for their potential activity as immunomodulators over their primary bactericidal or bacteriostatic activities. This study reports the influence of macrolides, spiramycin and dirithromycin on IL1 beta production. Mononuclear cells, isolated from healthy human volunteers, were preincubated with macrolides (0.1 to 500 micrograms/ml) and stimulated by Escherichia coli lipopolysaccharide. Then, IL1 beta production was detected by western blotting analysis. At therapeutic concentrations, dirithromycin and spiramycin seemed to enhance IL1 beta production by LPS-stimulated cells, with +37 per cent and +28 per cent at 1 microgram/ml respectively. At supratherapeutic concentrations, these drugs seemed to inhibit IL1 beta production through protein kinase C inhibition, with inhibitory concentrations 50 per cent of 378 micrograms/ml for dirithromycin and 234 micrograms/ml for spiramycin. So, macrolides may modulate the host defence system through their influence on cytokine production.

Effects of PVC bags sterilization process on the 5-fluorouracil stability

The stability and compatibility of 5-fluorouracil (5-FU) in undiluted or diluted admixtures stored in beta-radiation sterilized portable poly(vinyl chloride) (PVC) infusion bags were investigated. Admixtures containing 5-FU 50 mg ml(-1) not diluted or 25 mg ml(-1) diluted in 0.9% sodium chloride injection were placed in 100 or 250 ml empty PVC reservoirs sterilized initially by beta-irradiation. They were protected from light and placed at 37 degrees C. Two ml quantities were withdrawn immediately after preparation and after storage for 1, 2, 3, 4, 5, 6, 7 and 14 days. For each condition, samples from each admixture were tested for drug concentration by stability-indicating high-performance liquid chromatography. The admixtures were also monitored for precipitation, color change and pH. Evaporative water loss from the containers was also measured. 5-FU was compatible with PVC containers in all tested conditions for 14 days. No loss of drug and no color change were detected throughout the storage period. pH values were stable and neither precipitation nor loss of water through the reservoirs was observed when drug 50 or 25 mg ml(-1) (diluted using 0.9% sodium chloride) was stored in 100 ml capacity polyvinyl PVC bags. However, when stored in 250 ml capacity PVC bags, the 5-FU solution showed precipitation after 13 and 14 days of storage, but no drug loss was detected due to a substantial loss of water. The precipitation of the drug was due to the decrease of pH induced by the dehydrochlorination of PVC during beta-irradiation leading to the formation of hydrochloric acid in solution. Differences observed between 100 and 250 ml capacity bags can be explained by the greater area of PVC present in 250 ml reservoirs, and consequently more HCl formed. Finally, more plasticizer, di-(2-ethylhexyl) phthalate (DEHP), was then detected in drug solutions stored in 250 ml PVC bags. So, we recommend the use of 100 ml bags to store 5-FU at longer storage times and higher temperatures.

Differential regulation of killer cell Ig-like receptors and CD94 lectin-like dimers on NK and T lymphocytes from HIV-1-infected individuals

NK and T lymphocytes share various cell surface receptors, including NK receptors for MHC class I molecules (NKR). NKR include killer cell Ig-like receptors (KIR) and lectin-like dimers which are composed of the invariant CD94 associated with a variety of NKG2 molecules. The combination of KIR and CD94/NKG2 dimers expressed on NK and T cell subsets defines a repertoire of MHC class I recognition. Engagement of NKR by cognate MHC class I molecules governs T and NK cell activation. We investigated the NKR distribution on NK and T cell subsets from uninfected and HIV-infected individuals, according to the clinical status, the absolute numbers of CD4+ T cells as well as the plasmatic viral load of the patients. We show that the KIR distribution on NK cells is not affected by HIV-1 infection, whereas the absolute numbers of T cells expressing specific KIR members (CD158b, p70) transiently increase in early stages of HIV infection. By contrast, the percentages of NK and T cells which express CD94 dimers increase in parallel with the disease. These results document a differential regulation of KIR and CD94 lectin-like dimers during the course of a chronic viral infection in humans and further suggest that both types of NKR are independently regulated.

Exposure of hemodialysis patients to di-2-ethylhexyl phthalate

The migration of di-2-ethylhexyl phthalate (DEHP) from dialyzers was studied in 21 patients with chronic renal failure undergoing maintenance hemodialysis. The circulating concentrations of DEHP were measured by high performance liquid chromatography in blood of patients obtained from the inlet and the outlet of the dialyzer during a 4-h dialysis session. During treatment of renal failure using plasticized tubing, the plasma level of DEHP increased. On average, an estimated 75.2 mg of DEHP was extracted from the dialyzer during a single dialysis session, with a range of 44.3-197. 1 mg. On the other hand, the total amount of DEHP retained by the patient during the dialysis session was evaluated by the difference between the AUCout and the AUCin and ranged from 3.6 to 59.6 mg. The rate of extraction of DEHP from the dialyzer was correlated (r=0.705, P<0.05) with serum lipid content (cholesterol and triglyceride).So, we confirmed that patients on hemodialysis are always regularly exposed to considerable amounts of DEHP. However, several metabolic effects have been reported in various animal species following treatment with DEHP, such as changes in lipid metabolism and in hepatic microsomal drug-metabolizing enzyme activities. DEHP is now a well-known hepatic peroxisomal proliferator in rodents and an inducer of many peroxisomal and non-peroxisomal enzymes. So, lipid metabolism modifications and hepatic changes observed in hemodialysis patients could be explained from chronic exposition to DEHP. In the coming years, it seems necessary to reconsider the use of DEHP as a plasticizer in medical devices. Highly unacceptable amounts of DEHP leached during the dialysis session could be easily avoided by careful selection of hemodialysis tubing.

Selection criteria for internal rectal prolapse repair by Delorme's transrectal excision

PURPOSE

The aim of this study was to review our results of Delorme's transrectal excision for internal rectal prolapse, with a view to determining preoperative selection criteria associated with a satisfactory outcome.

METHODS

Between 1992 and 1998, 20 patients with internal rectal prolapse underwent Delorme's transrectal excision. The last patient was excluded from the study because of a follow-up period shorter than six months. The remaining 19 patients were prospectively followed up and classified into two groups according to their preoperative selection criteria. Group I consisted of eight patients operated on between January 1992 and October 1993 who were selected for surgery after medical treatment during a three-month period failed to improve symptoms. Initial results were reviewed, with a follow-up of at least six months, to assess predictive criteria correlating with poorer surgical outcome. These adverse criteria were used to exclude patients from selection into Group II, which included 11 patients operated on between June 1994 and June 1997. In each group the degree of improvement of symptoms was graded: Grade 1 = complete improvement with resolution of all symptoms; Grade 2 = significant improvement with resolution of dyschezia but not of other symptoms; Grade 3 = no improvement; and Grade 4 = worsened condition or reoperation. The two groups were compared according to ultimate outcomes.

RESULTS

Of the Group I patients, three had preoperative chronic diarrhea, one had proximal internal rectal prolapse with rectosacral separation at defecography, and the other two were incontinent to liquid stool. An additional patient had incontinence to liquid stool but no diarrhea. Three other patients had major perineal descent (>9 cm). Results were Grade 1 for one patient, Grade 2 for one patient, Grade 3 for five patients, and Grade 4 for one patient (subsequent abdominal rectopexy). Data review showed that proximal internal prolapse with rectosacral separation at defecography, preoperative chronic diarrhea, fecal incontinence, and descending perineum (>9 cm on straining) were associated with a poorer outcome (Grades 3 and 4). These adverse criteria were used to exclude patients from selection into Group II. In this group results were Grade 1 for seven patients and Grade 2 for four patients. During the course of follow-up (mean, 43; standard deviation, 19; range, 8-73 months), outcome was better in Group II (P = 0.007). CONCLUSION. These data suggest that a favorable outcome can be achieved after Delorme's transrectal excision for internal rectal prolapse by applying stringent patient-selection criteria.

Comparative oxidation of loxapine and clozapine by human neutrophils

The clozapine-induced agranulocytosis could be due to the formation of a reactive intermediate formed in polymorphonuclear neutrophils and granulocyte precursors with the myeloperoxidase-hydrogen peroxide system. On the contrary, no case of agranulocytosis has been described for loxapine, an other neuroleptic drug with a very close structural analogy. We have compared the clozapine and loxapine interaction with the oxidative burst and particularly with this enzymatic complex. On the one hand, the assay of the oxidative species demonstrated a different impact for the two neuroleptics. The 50% inhibitory concentration was 92 microM for hydrogen peroxide and 40 microM for hypochlorous acid for loxapine. The loxapine target is located before the myeloperoxidase-hydrogen peroxide system in the oxidative stream, whereas clozapine diverts the chlorination pathway of the enzyme. On the other hand, the in vitro metabolism of drugs by the myeloperoxidase-hydrogen peroxide system has been investigated by mass spectrometry. Loxapine remains inert but clozapine undergoes the oxidation. The glutathione or ascorbate addition in the medium leads to a removal of the oxidation. Glutathione is able to trap the toxic intermediate and could avoid its formation.

Time and concentration dependent influence of dirithromycin on neutrophils oxidative burst

Dirithromycin is a 14-membered macrolide antibiotic, well known to yield high intragranulocytic levels after several hour exposure. We chose therefore to investigate oxidative metabolism after prolonged incubation periods with neutrophils. Neutrophil generation of reactive oxygen species, represented by superoxide anion, was assessed after fMLP or Staphylococcus aureus-induced activation of the respiratory burst. Cellular uptake of the drug was assessed concurrently, in order to attempt a correlation with time-dependent modifications of the cellular oxidative status. For 1 hour exposure time, a pro-oxidant effect was reported for lower concentrations, achievable during therapeutic administration, whereas the highest ones promoted a potent anti-oxidant effect. After prolonged incubation times, the anti-oxidant effect alone was reported, with time-dependent modifications of IC50 values. These values could be correlated with intracellular accumulation of the drug. The anti-inflammatory activity reported here for high dirithromycin concentrations, could be nevertheless clinically relevant, since dirithromycin cellular uptake extends beyond 4 hours.

Combination antiretroviral therapy including ritonavir in children infected with human immunodeficiency

OBJECTIVE

To assess the efficacy of combination therapy that includes ritonavir in HIV-1 infected children.

DESIGN

A monocentric retrospective study.

PATIENTS AND METHODS

Twenty-two children with a minimum follow-up of 6 months under triple therapy including ritonavir were analysed for treatment efficacy. At entry, all the patients were protease inhibitor naive and all but two had received previous antiretroviral therapy during a median period of 5 years. Their initial median CD4+ lymphocyte count and viral load were 121 x 10(6)/l and 5.08 log10 copies/ml, respectively. Clinical and biological evaluation included clinical assessment every 6 weeks and determination of CD4 cell count and HIV-RNA concentration every 3 months.

RESULTS

Median length of follow-up on triple therapy was 15 months (range: 7-21 months). Neither progression in the CDC classification nor death occurred. No significant change in mean weight SD scores was noted when baseline values were compared with values obtained after 1 year of triple therapy. Median CD4 count increases were of 210 x 10(6)/l, 415 x 10(6)/l, and 472 x 10(6)/l cells at 6, 12, and 18 months, respectively. Among the patients baseline characteristics, neither age nor initial CD4 cells count influenced the magnitude of immunologic improvement. There were median decreases of 1.14, 0.95, and 1.5 log10 per ml of plasma in the concentration of viral RNA at 6, 12, and 18 months respectively. Seven patients maintained an undetectable viral load when under treatment. The introduction of at least one new reverse transcriptase inhibitor at the initiation of triple therapy correlated significantly with a greater viral suppression.

CONCLUSION

Despite variable viral response, antiretroviral-experienced HIV-infected children demonstrated a substantial CD4 cell increase during a median period of 15 months of ritonavir containing combination therapy.

Pharmacokinetics of midazolam: comparison of sublingual and intravenous routes in rabbit

In France, the legal routes used to administer midazolam to a patient are intravenously and intramuscularly. For anaesthetists, these routes are not well adapted to paediatric use; they lead to pain at injection site and stress on children. The sublingual route should be a good compromise between stress and quick efficiency. We have developed a sublingual tablet of midazolam. The aim of the present investigation is to compare the pharmacokinetic parameters of midazolam tablets administered by the sublingual and intravenous routes in 6 rabbits to determine the bioequivalence between these routes. We have estimated the 1-hydroxy-midazolam serum level by difference between RRA and HPLC values. By the sublingual route, midazolam absorption is substantial and fast. The statistical analysis, on data obtained with HPLC dosage, shows no significant difference between pharmacokinetic parameter values calculated after intravenous and sublingual administration (0.5 mg). The absolute bioavailability was close to 100%. With RRA dosage, however, AUCs were greater than those obtained by HPLC dosage (174%). 1-hydroxy-midazolam seems to have a great importance in BZD activity. To estimate the bioequivalence between intravenous and sublingual midazolam administration, it is necessary to take into account the active metabolites.

A case report: CD8 expression in B-cell chronic lymphocytic leukemia (B-CLL). Prognostic significance of the aberrant CD8 expression

The human CD8 molecule is usually expressed on T lymphocytes or natural killer cells but not on normal B cells. Over a course of 5 years, we followed a case of B-CLL which aberrantly expressed the CD8 molecule. During this period, the clinical and hematological conditions of the patient were stable. This B-CLL presented a typical immunophenotype (HLA DR+, CD19+, CD5+, CD23+) with monotypic expression of surface immunoglobulin light chain kappa. We confirmed the CD8 expression on these leukemia cells by using double labelling and different antibodies directed against this antigen. We measured the quantitative expression of the CD8 molecule. The number of CD8 molecules per cell was clearly lower on these malignant B cells than on normal T lymphocytes. In order to evaluate the prognostic significance of this CD8 expression, we quantitated in parallel other markers such as CD5, CD23, CD22, CD11c. During 5 years, this aberrant CD8 expression persisted and was associated with an increase of the CD23 and a decrease of CD22 levels, known to correlate with a good prognosis in agreement with the karyotype analysis. Altogether our results led us to conclude that the aberrant CD8 expression in this case of B-CLL may correlate with a non-aggressive form of lymphoproliferative disorder.

In vitro activity of aminoglycosides on the respiratory burst response in human polymorphonuclear neutrophils

In response to phagocytosis of microbes or chemical stimuli, neutrophils generate reactive oxygen species which represent the major bactericidal mechanism of these cells. We have investigated the influence of aminoglycosides (amikacin, gentamicin, netilmicin and tobramycin), antibiotics with a marked concentration-dependent killing effect, on the human neutrophil oxidative burst represented by the release of hydrogen peroxide. This study was performed using time-dependent cellular experiments and a cell-free system. In the cellular model, 2-h incubation with amikacin (ranging from 10 mg/l to 1 g/l), enhanced hydrogen peroxide release by stimulated human neutrophils. At higher concentrations (1 to 5 g/l), hydrogen peroxide production was decreased. No significant effects were observed with the other aminoglycosides at concentrations ranging from 10 mg/l to 2.5 g/l. The pro-oxidant activity of amikacin may be due to a cellular mechanism through oxidative metabolism of human neutrophils as demonstrated in the cell washing experiment, whereas the antioxidant activity observed for higher concentrations may be a result of a scavenging effect as demonstrated in the cell-free system. The enhanced of hydrogen peroxide production observed for therapeutic concentrations of amikacin could be a beneficial effect for neutrophil bactericidal functions.